NETCAR-Analyzer V1.6.1 User Manual - RealTime-at-Work
Contents
1. Analysis Windows Help Minimum Wert Buffer Utilization Load Indicator As a result a progress bar appears although in most cases the analysis will not take more than a few seconds WCRT calculation of project pomertrainso Overall Progress Analyzing frames Cancel When the analysis is done a new column appears for each frame it contains the WCRT induced by the Zero offset configuration da NETCAR Analyzer Evaluation version not for production use o o Be x Offsets Analysis Windows Help N 7 rar Ar aval ot er La fa Joc wal gas spi odt cad ata do g m to pis 1a o land a rl r ral xm I Frames Offset powertrain 50 Frame Name EcuName Frameld Period Length ae gt cao leo mo o frlo res frames1 Eo lrj7e2 20 4 elo ft tones fo e 500 fa fejo em famoso ewo jes jo fo fujo pm frames2 Eu fejs jo e fejo zema emess fewo zje fo fe fj e _QueuePolicy fame20 Ewi r is oo jo rjo s254 tame ewa feln ro fa feo us o fame22 out lrjes2 mo s fejo jura frame23_ out lrjes 50 e feo mom frame24 Ecua lr 3s7 w0 8 fejo iza frame25 Ecuatii o fz efor fame26 Bout t311 w00 fe fejo ras fame27 Ecu lrjess 500 e fejo ft eee romes fewa fejes o e o esa fame293 Et fejs quo e fejo i2 frame30 Ewa fej o 6 fe o zm frame3 Bout ija o0 2 Jrjo 15 024 femesz wa as fo aojo fesa fremess Bout o fej jo e feo fes famea Ewa o ejos o eejo qua2. 5000 frame Ecu 0 64 20 framebo Ecu O framed Ecu O EcuMame QueuePolicy framez Ecu 1 Hpt framez Ecu 1 Ecu 1 Hpt frames Ecu Load Ecu_2 Hot frames Ecu_1 Ecu_3 Hpf framedd Ecu_1 pans Hpi framez5 Ecu 1 Ecu_5 Hpt Ecu_6 Hpt Ecu Hpt Ecu O Hpt frame2b Ecu 1 frames Ecu 1 frameso Ecu 1 framed Ecu 1 frames Ecu 1 Ecu 9 Hpf frame3 Ecu 1 framede Ecu 1 frameds Ecu 1 frames4 Ecu frame35 Ecu 1 frame36 Ecu 1 frames Ecu frame3 Ecu 1 framed Ecu 1 SJ E da a ae Do ae a DD Dam ee DD ae a Om Oljolj oj oj Ooj oj oOj oj Ooj o Ojo jOoOj OoOjOoO j j Opj o j oOj Ooj OoOj oOoj OoVj OlO 02011 RTaW 29 49 NETCAR AnaLyzer V1 6 1 User ManuaL 3 2 Data editing In this section we describe how new data entities such as buses and frames can be created Section 3 2 1 modified Section 3 2 2 or deleted Section 3 2 3 3 2 1 Creation Additional ECUs or frames can be created by entering values for their properties in the last line of the concerned table The following screen shot shows the example of a new ECU Ecu_6 Hpf Ecu r Hpf x Ecu 5 Hpf al Ecu 9 Hp E fo led E Advise do not save the file while values are missing for some of the attributes of a new ECU or frame because this will result in a corrupted file that can not be Opened anymore 3 2 2 Modification The properties of existing ECUs and frames can directly be edited in the tables For this purpose you need to
3. p f z p AE EcuName QueuePolicy frame 20 Ecu 1 j m2 fie fum frame 24 frame 25 framez6 Ecu 5 frame Ecu amp framed Bay frame Ecu frame 30 Ecu 3 frame31 frames frame 33 frame 34 frame 35 frame 36 froma 17 662 642 357 136 1311 258 EB 19 43 das 219 178 115 103 ae Ecu 3 Ecu 4 j f p j f aa Ma a a a Ma e Ma pa e a Ma a i e papa qa ao SS O E O ROM O pap O REM O WEB O REM O paj O As can be noticed besides the basic frame properties like the identifier or the period one transmission offset configuration is defined that assigns the offset O to every frame column Offset Zero Such an offset configuration means the following e When frame communication starts one instance of each frame is instantiated ready for being sent e The second instance of each frame is instantiated after a time equal to Its period which is generally not the same for all frames e After a time equal to the so called hyper period smallest common multiple of all frame periods all frames are again instantiated at the same time This kind of situation is also known as critical instant in the worst case analysis literature 1 2011 RTaW 6 49 NETCAR AnaLyzer V1 6 1 User ManuaAL Let us now compute the worst case response time VVCRT of the frames For this purpose select the Wert entry from the Analysis menu
4. The send buffers may be a scarce resource but their limited number can lead to problems like the so called inner priority inversion see 4 An inner priority inversion occurs when a frame instance is ready for transmission and has a priority higher then that of all instances of other frames 02011 RTaW 39 49 NETCAR AnaLyzer V1 6 1 User ManuaL currently in the transmission buffer s but the former can not participate in the arbitration because it is not yet located in a transmission buffer since these are all occupied A simple but costly and not always realizable solution consists in having as much send buffers as different frames send by the ECU But the number of simultaneously waiting frames can be much smaller especially if offsets are used for sending the frames Knowing the worst case number of simultaneously waiting frames would allow to choose exactly the needed number of send buffers and to perform this way an efficient and safe design choice NETCAR Analyzer does exactly allow this by computing for each ECU e an efficient upper bound on the highest number of simultaneously waiting frames Max Buffer an efficient upper bound on the highest number of frames still in the send buffer s when the COM task adds new frames Max Backlog If the Maximal Backlog is zero then the following strategy for inner priority Inversion avoidance may be used if the periodic COM task instantiates frames in th
5. Toulouse France January 29 February 1 2008 2 M Grenier J Goossens N Navet Near Optimal Fixed Priority Preemptive scheduling of Offset Free Systems Proc of the 14th International Conference on Network and Systems RINS 2006 Poitiers France May 30 31 2006 3 N Navet A Monot J Migge Frame latency evaluation when simulation and analysis alone are not enough Sth IEEE International Workshop on Factory Communication Systems WFCS2010Q Industry Day May 19 2010 Available at url http www realtimeatwork com page_id 5 4 Specification of CAN Interface AUTOSAR v4 0 2009 2011 RTaW 48 49 NETCAR AnaLyzer V1 6 1 User ManuaL 5 N Navet Y Q Song F Simonot Worst Case Deadline Failure Probability in Real Time Applications Distributed over CAN Controller Area Network Journal of systems Architecture Elsevier Science vol 46 n 7 2000 Available at url http www realtimeatwork com page_id 5 6 R Davis A Burns R Bril J Lukkien Controller Area Network CAN schedulability analysis Refuted revisited and revised Real Time Systems vol 35 n 3 2007 2011 RTaW 49 49
6. button 2011 RTaW 14 49 NETCAR AnaLyzer V1 6 1 User ManuaL Plot CANETCAR AnalyzeriTutorial landmark 2 xml ES Sr Reload Zero Ar Rel Load SOA peot ay 10 20 30 40 50 60 r 40 g Frame priority rank The graphic shows that the relative loads are now all below 40 Notice that the periodic load of the bus is not changed by transmission offsets still equal to 50 But transmission offsets allow to better exploit the bandwidth with respect to deadlines with a relative load of under 40 for all frames there is more slack for additional high priority frames In this section we have seen that the SOA algorithm is able to produce instantaneously an offset configuration that induces very low worst case response times Note that is mainly due to the fact that the frames have quasi harmonic periods shorter periods are dividers of many of the longer periods In order to get an idea of how good the algorithm performs let us compute the WCRT for random offsets For this purpose go to the Offsets menu and select the All entry for the Random algorithm and compute the worst case response times for the generated offsets Furthermore go to the Analysis menu and select the Wert Lower Bound entry Analysis Windows Help Weert Buffer Utilization Load Indicator 2011 RTaW 15 49 NETCAR AnaLyzer V1 6 1 User ManuaL This computes lower bounds below which worst
7. otherwise the menu entries will remain grayed out Offsets DOA Offsets Shaping Offsets SOA Offsets Random b This brings up the configuration dialog g Offset local search optimization 0 o ye ee So Offset local search range 9 Local Search Frame Selection Search criterion based on least pronty frame WCRT Search criterion based on the 10 least pronty frame WERT 6 Search criterion based on allthe frames WCRT Search criterion based on custom frames WCRT frame 11 frame12 frame13 frame14 E frame 15 frame16 E fra Select Search criterion based on custom frames WCRT mark frame12 in tab 3 mark frame62 in tab 1 and push the Ok button Then select the Offset SOA configuration 2011 RTaW 21 49 NETCAR AnaLyzer V1 6 1 User ManuaL Offset selection Select which offset should be used for this operation As a result the optimization algorithm starts its work which may take 10 to 2U minutes Offsets Local Search Progress Improvement realized Local Search Area covered 8 Improving offset of TEA When the optimization process has finished push the Done button A new column has been generated with the optimized offsets Offset SOA 1 Modified offsets are displayed in green 2011 RTaW 22 49 NETCAR AnaLyzer V1 6 1 User ManuaAL O E fn 1 244 11 02 757 TT 3 im fura foi fo a am
8. program folder in the Windows Start menu if you have installed tt Csvellca l 1 0 i R T a ty SeaMonkey E Chesticat 1 0 Sun VirtualBox Guest Additions Minplus Console 1 1 2 P Wh License if Uninstall TortoiseSvN NETCAR Analyzer d ESA ESA The GUI of Dbc Nca is the following E Dbc to NETCAR ANalyzer v1 1 0 www realtimeatwork com x NETCAR Analyzer data importer for Vector Dbc file Copyright c 2011 RealTime at Work RTaVV All Rights Reserved Overview This tool extracts messages from a Vector Dbc file and exports them as a NETCAR Anayzer file Details A message is exported as a periodic frame if a period is defined through a custom attribute and ifthe message is send by a network node A frame offset is exported if an offset is defined through a custom attribute A network node is exported as an ecu if it sends at least one message the name of custum attributes needs to be provided the Vector Tool Chain Attribute names GenMsgCyclelime and GenMsgStanDelayTime are proposed by default for period and offset attributes but can be edited below Note the bus speed must be provided because we do not know where to find it the Dbc file Vector Dbc input file Bus speed k bits s Custom attribute for period GenMsgCyclelime Custom attribute for offset GenMsgStartDelayTime NETCAR Analyzer output file Lo select the Db
9. simply move the mouse pointer over the column title and wait a second WERT Rel Load R Random Zero Si YCRT ms computed with offsets Offset Random 3 4 2 Relative loads A hands on example is provided in Section 2 2 The relative load of a frame is the WURT of that frame expressed as percentage of the frames deadline i e the longest allowed response time Currently the period is considered to be the deadline and thus the frames response times must be shorter then the period lf a frame has for example a period and thus a deadline of 100ms and a WCRT of 33ms then the relative load is 33 A relative load of 33 means first of all that the deadline is meet In general as long as the relative load is below 100 the deadline is met A relative load of 33 also means that there is 66 slack time left This slack time could be used to add more higher priority frames How much and what kind of higher priority frames can be added without causing deadline overrun must be determined through the computation of WCRTs but a slack of 66 is a good synthetic indicator of the fact that there is indeed room left for adding frames Such a synthetic indicator is useful for monitoring at project Management level the evolution of resource usage because it hides the details such as the exact values of the deadlines and shows only an essential information about the resource 2011 RTaW 38 49 NETCAR AnaLyzer V1 6 1 User Ma
10. the generated offsets The resulting column is Wert SOA In order to make a comparative plot select Plot from the Analysis menu then check the Offset Zero and Offset SOA series Plotting Selection on did Select data to plot x ais ordering 4 WCRT Zero Priority order W WERT SOA E Rel Load Zero and finally push the Ok button The following graphic is then shown 2011 RTaW 13 49 NETCAR AnaLyzer V1 6 1 User ManuaL amp Plot C NETCAR Analyzer Tutorial landmark 2 xml 5 Analysis Ar WCRT Zero ar WERT SOA sw LHJM O 10 20 30 40 50 60 rd 40 g Frame priority rank As can be seen the offsets produced by the SOA algorithm significantly reduces the worst case response times of the frames The reason is that the transmission offsets do spread out the frame instantiation times so that the so called critical instant where an instance of each frame is ready for transmission at the same time can not occur anymore Let us also compare the relative loads For this purpose compute the relative loads for Wert SOA Load indicator in the Analysis menu Make sure that the frame table window has the focus otherwise the menu entries will remain grayed out To create the plot select Plot from the Analysis menu and check this time only the Rel Load Zero and Rel Load SOA series before pushing the Ok
11. 93 450 33 04 0 46 0 93 11 16 2 54 757 447 9 14 18 37 28 04 4 99 9 34 2 13 6 77 oe ee Offset SOA 1 100 EE In order to evaluate this optimization you should compute the corresponding WCRTs see Section 3 4 1 and the relative loads see Section 3 4 2 02011 RTaW 47 49 NETCAR AnaLyzer V1 6 1 User ManuaL 3 7 Exporting data 3 7 1 Copy Paste In any table you can select a range of cells and copy the contained data as table to word processors or spreadsheet tools In particular you can easily select an entire table by clicking on its left upper corner Frames N FrameName EcuName frame48 Ecu O frame51 Ecu O frame57 Ecu O frame60 Ecu 0 3 7 2 Import into RTaW Sim You can also import the NETCAR Analyzer files into RlaW Sim in order to complement the computed WCRT by statistics like the average response times or by quantiles the 90 quantile is a threshold that is overrun in 90 of the cases in the average It also allows to simulate the worst case scenarios that NETCAR Analyzer has identified for each of the computed WCRTs More information about RTaW Sim can be found here http www realtimeatwork com page_id 121 4 References 1 M Grenier L Havet N Navet Pushing the limits of CAN Scheduling frames with offsets provides a major performance boost Proc of the 4th European Congress Embedded Real Time Software ERTS 2006
12. the frame priorities are necessarily adjacent that would just be one possible case In our example the resulting graph looks like a line with steps The line segments are due to the fact that in the worst case each frame is basically preempted by One instance of every higher priority frame this leads to a slightly irregularly increasing shape due to the different frame lengths The steps are due to the fact that more than one instance of a same higher priority frame may preempt if the resulting response time becomes longer than the period of that higher priority frame The sample comprises seven 1Ums frames which may all together 2011 RTaW 9 49 NETCAR AnaLyzer V1 6 1 User ManuaL preempt twice as soon as the worst case response time become longer than 10ms this happens to frame60U for example When the response time is longer than 2Ums then three instances of the 1Ums frames and two instances of the 2Oms frame may preempt which leads to an even larger step 2 2 Compute load indicators A commonly used indicator for the bandwidth usage of a CAN bus ts the periodic load induced by a set of frames A periodic load of 50 for example means that half of the bandwidth is used The other way round it means that 50 of the bandwidth should be available for additional frames In the automotive industry however a periodic load of 50 is considered to be already too high additional frames would surely be transmitted over an addi
13. 1 2 Lb Tortoises vl NETCAR Analyzer The GUI of Csv2Nca is the following 2011 RTaW 34 49 NETCAR AnaLyzer V1 6 1 User ManuaL 0 Csv to NETCAR Analyzer v1 1 0 wumrealtimeatworkcom us E lo 2 NETCAR Analyzer data transformer for csv file Copyright c 2011 RealTime at WVork RTaVV All Rights Reserved Overview This tool extracts messages from a Csv file and exports them as a NETCAR Anayzer file Details The csv file must use the as separator and have the following format RTaW Sim Csv Format Bus Name Speed Frames LO Name Identifier Payload frame 01 23 frame 02 345 frame 03 122 frame 04 212 frame 05 341 frame 06 78 frame 07 976 frame 08 u 52 frame 09 36 frame 10 6 O core SS OS SS ira Csv input file NETCAR Analyzer output file select the CSV input file and NETCAR Analyzer output file by clicking on the triangle on the right of the corresponding text box Finally click Transform and go back to NETCAR Analyzer to open the imported file 3 3 4 Import model from Dbc file DBC is a proprietary VECTOR Informatik Gmbh file format that is very widely used for describing CAN based communication systems For users having subscribed a professional support contract RTaW provides a tool for transforming DBC files into NETCAR Analyzer files 2011 RTaW 35 49 NETCAR AnaLyzer V1 6 1 User ManuaL This tool is called DbcoNca and located in the RTaW
14. 79 95 10 0 3 284 32 84 E 42S E 379 40 0 13 134 37 84 hame m 171 20 0 6 534 37 67 cas E E 378 40 0 12 984 32 46 aT bioi frame68 A 358 40 5 0 12 564 31 41 frameB0 Eou 8 332 40 0 12 084 30 21 Ecu 8 frame75 Ed 257 40 0 9 434 23 59 Ecu 3 ane ar 236 40 0 9 164 2291 i EE E o G lo lee faes 40 7 M 0 20 edo frame 10 cu 114 As can be seen the relative load of one of the frames is around 75 which Is a better indicator for the fact that only a little part of the bandwidth remains available at priorities higher than that of frame62 because the wort case response time of that frame is already close to the deadline period To get a better idea of how the relative load bottle necks are distributed chose the Plot entry from the Analysis menu select the Rel Load Zero series and push the Ok button 2011 RTaW 11 49 NETCAR AnaLyzer V1 6 1 User ManuaL J Plot C Users jorn syvn netcar Netcar Analyser docs help odt data T utorial landmark 1 xml L Analysis RetLoad Zero u peoT jay D 10 20 30 40 50 p rd BO g0 Frame priority rank Remember that the X range represents the frames in order of their priorities see Section 2 1 The graphic shows that relative loads are rather high among the higher priority frames left part and that adding an additional frame among the higher priority frames in the left most third is very likely
15. LHJM Dish iy de TO ey E i ke ake ake A Aiia a Page ae aie T og aie ket A de i EE Aii Ah igri orii gt LLL ae ae MOS de Th ty A E Ba ee E MV it 4 0 10 20 30 40 50 60 gi B 90 Frame priority rank 3 6 Defining and optimizing transmission offsets 3 6 1 Import When a frame set is imported the offsets are also automatically imported 3 6 2 Manual editing Any existing offset configuration can directly be edited in the frame table Advise do not change the offset values of an offset configuration for which WCETs have already been computed because otherwise the WCRT values may become inconsistent with respect to the offsets 3 6 3 Creation of a new optimized offset configuration A hands on example is provided in Section 2 3 The Offsets menu contains several entries for algorithms that create new offset configurations e DOA Algorithm aims at minimizing resulting WCET e Shaping Algorithm aims at minimizing resulting WCET 2011 RTaW 43 49 NETCAR AnaLyzer V1 6 1 User ManuaL e SOA Algorithm aims at minimizing resulting WCET e Random random offsets useful for comparison these algorithms are only available to users that have subscribed a professional Support contract Computing the corresponding WCET see Section 3 4 1 and plotting them against each other see Section 3 0 allows to identify the one that produces the best WCET depending on the characteristics of the frames and the timing req
16. R law Real Time at Work NETCAR Analyzer V1 6 1 User Manual Author Jorn Migge Verifier Nicolas Navet Lionel Havet Version DRAFT Date 21 2 2011 Contents TINTOU O a 3 1 1 Licence ofthe Sowar ccs sec sccerz Severs Severs Severs Sees a Sees Secs Saves Secs Secs Sece Secon Secor aan 3 Te INSCANA BIA ee 4 To UDIT 4 1 4 New releases and updates on eessssssssssssssssssessssesssssssssssssssssssssssssssesssuessssessssessssssssosessasessossssasessaeesees D a O e e EE O 2 1 Compute worst case response times of CAN frames eternas 5 2 2 Compute load INGICACOPS wou ccesssseesseeseseessseessseessseessseessseeassesasseeassneasseeasseeasseeassneassneasaneassneaseneenenen 10 2 3 Generate optimized offset configurationS irritar erereaerterearerre rea eererereerares 12 2 4 Compute worst case transmission buffer occupationsS eres 16 co PUI SS GU ON SS session nena navamecassoasagt 20 ED Eromena OCS 6 ee ee ee eee do o Reference MANU orense p s p re p s aber diind added eddie indolor eng 30 ol Overview ro ENO UA en nn SU Se LC CONNOR RS OO SOR SOS 31 Sed RCA CON he ee eee 31 Dee INI CEEE NO A asst asec ocetasaas avons escactee then 31 Oaoa DEIC O Pen ne ee RN eee eee eee 32 3 3 Open or import of existing MOEIS cccssssssssesssessesssssssessssessssessssessssersssessssessesessssessssersssetess 32 Ss Open Menu CIR esisiini naea aaaeeeaei aaaea eeina So 3 3 2 Recent files Menu CID x cssccncaccecascucoacadecs
17. RTs of all or a subset of frames become smaller or remain the same The WCRI of the frames that do not belong to the subset may Increase This allows for instance to reduce the relative load of certain frames as we will see in this section To perform this tutorial either continue with the data resulting from the previous tutorials or open the file Tutorial landmark 3 xml from the samples tutorials folder Remember the relative loads for the SOA offsets based WCRTs see Section 2 2 The plot of these relative loads looks like this amp Plot C NETCAR Analyzer Tutorial landrmark 3_SOA x ml o lE bE _ Analysis Ar Reload SOA po e peOT jaM aa 10 20 30 40 50 60 rg Bl oO Frame priority rank In the above screen shot we have located the mouse pointer over the highest point in order to identify the corresponding frame According to the x coordinate It Is the frame with id 1839 decimal format If we sort the frame table according to the Frameld column we can easily find the corresponding frame name frame12 The second highest relative load is that of the frame called frame62 with id 193 2011 RTaW 20 49 NETCAR AnaLyzer V1 6 1 User ManuaL Imagine that we would like to reduce the relative loads for these frames by changing the offsets appropriately For this purpose select the Optimize Offsets entry from the Offsets menu make sure the frame table window has the focus
18. T o E z le Keep the Search criterion based on all frame WCRT selected and click Start After the initialization phase the progress bar starts to move Offsets Local Search Progress Improvement realized Local Search rea covered Improving offset of Status When the optimization has finished click the Done button Then compute the worst case response times and make a comparison plot 2011 RTaW 27 49 NETCAR AnaLyzer V1 6 1 User ManuaAL dr WERT SOA WERT SOA 40 20 60 Frame priority rank As can be seen after optimization of the offsets of the new frames all worst case response times are below Ooms 2011 RTaW 28 49 NETCAR AnaLyzer V1 6 1 User ManuaL 3 Reference Manual This section provides a detailed description of all functionality offered by the NETCAR Analyzer tool 3 1 Overview of the GUI Besides the classical menu bar at the top See the figure below the user interface is subdivided into three parts 1 bus properties in the upper left part 2 connected ECUs and their properties in the lower left part 3 frames and their properties tn the right part d Fie Edit Offsets Analysis Windows Network Project power rain Sic FrameMame EcuMame Frameld Period Length EaudRate FOO Ecu bl 200 frame5 Ecu 0 TEZ 200 frameb Ecu 0 J363 FOL Granularity us
19. ansmission buffer s 2011 RTaW 16 49 NETCAR AnaLyzer V1 6 1 User ManuaL but the former can not participate in the arbitration because It is not yet located in a transmission buffer since these are all occupied When the worst case number of waiting frames is known a simple strategy consists in allocating enough buffers for transmission so that even in the worst case all frames can be stored in a free transmission buffer an thus no inner priority inversion may occur Notices that the worst case number of waiting frames can be much smaller than the total number of frames that a controller can potentially send especially if transmission offsets are used To perform this tutorial either continue with the data resulting from the previous tutorials or open the data set Tutorial landmark 3 xml from the samples tutorials folder Then go to the Analysis menu and select the Buffer Utilization entry and choose the the Ok button Analysis Windows Help wrt Wickk Lower Bound Buffer Utilization Load Indicator Flot Gateway Offset selection Select which offset should be used for this operation As a result the following window appears 2011 RTaW Offset Zero configuration in the resulting dialog before pushing 17 49 NETCAR AnaLyzer V1 6 1 User ManuaL KA Maximum Buffer Utilization Phas CUsersijornineteart E Ecu Mas Buffer Max BackLog j oud o
20. asaspudascsseasadecsasacpudascseasa docs sacpudascdeauadaessacpudascudeaahdapscbceete 33 So Import modelirom Cev ULM See eleclcclclecelocerloaenlocasstocdsteesestanecacudes 33 3 9 4 Import model TROCO corretora 36 3 4 Worst case ANAIS va seccccsnitesessinnscessesstecca ance tran unis esunteccstoneitosnanusebiedeenencttunibaracbeceabn 36 3 4 1 Worst case response times Of frames temer rem rermereree cera rerre cera rerrerereereresa 38 o4 a Pelative JOAO ape pe O DCD PC RPC PO PC a 3g 3 4 3 Worst case transmission buffer utilizatiON restaram reeeerere rare rerearasa 41 So ViSudizing results ds CUVE S as ra SU eee tee aaa 43 3 6 Defining and optimizing transmission OffSEUS qu ecssesseceseseseseseeseeesseeeeeeeetseeteeeees 44 SO DMD Gi eno en o eee 44 e Manuae e eai E E ERE E EEE EEEE 44 3 6 3 Creation of a new Optimized offset configuration iene 44 Soe Oplimization OF Specht VGN scene 45 2011 RTaW 1 49 NETCAR AnaLyzer V1 6 1 User ManuaL L EDORA Aa ae RR RR RR neue cease RR RR 49 oe ee COD ROC eee eee ee ee ee 49 oF ce MVD OPE ATIC RA VALSA e 49 RCC d Ir 49 2011 RTaW 2 49 NETCAR AnaLyzer V1 6 1 User ManuaL 1 Introduction NETCAR Analyzer is a worst case timing analysis tool that helps the system designer optimize the scheduling of frames on Controller Area Network CAN and check that the requirements on transmission delays are met NETCAR Analyzer implements a set of proprietary configuration algorithms
21. c input file and NETCAR Analyzer output file by clicking on the triangle on the right of the corresponding text box Then you need to provide the bus speed because because the DBC file does not contain this information Furthermore there are no standard attribute names for frame periods and frame transmission offsets The dialog proposes by default the custom attribute names 02011 RTaW 36 49 NETCAR AnaLyzer V1 6 1 User ManuaL that are used by the Vector Tool Chain You can edit the fields and change the names according to your needs Finally click Transform and go back to NETCAR Analyzer to open the imported file 3 4 Worst case analysis The analysis algorithms implemented in the tool perform a so called worst case analysis given the properties of the bus and the frames the algorithms determine the scenario in which some quantity reaches its worst value The knowledge of these worst values allows to check if a certain system configuration allows correct functioning even in the worst case The quantities of interest here are frame response times see Section 3 4 1 and transmission buffer utilization see Section 3 4 3 3 4 1 Worst case response times of frames A hands on example is provided in Section 2 1 The response time of a frame is the delay between the moment when it is instantiated in the sender ECU and the moment where the transmission of the frame ends and thus it is available in reception buffers of the
22. case response times can not be pushed by any offset algorithm It does not mean that this lower bound can be reached by any algorithm but when worst case response times are already close to that lower bound then it is not worth trying to improve the offsets any further A comparative plot of the worst case response times induced by the different offsets and the lower bound shows that the SOA algorithm 1 produces offsets that are significantly better than random offsets and are thus worth using 2 produces very good worst case response times that are probably difficult to improve globally the optimization of specific worst case response times Is shown in Section 2 5 amp Plot C NETCAR Analyzer Tutorial landmark 2 xml EEB Analysis 40 WCRT Zero de WORT SOA gt WCRT Random ar Lower Bound of WORT sw LHIM ba Pan si AA NA dl A RA Ay Ah ki A NTE dita Ae Het A Ok yee ta ie EEE Eee eee SRR NNN i O 10 20 40 40 50 60 T 40 g Frame priority rank 2 4 Compute worst case transmission buffer occupations The worst case number of frames that may be waiting at the same time for transmission in a CAN controller is a useful information when choosing a strategy to avoid the so called inner priority inversion see 4 An inner priority inversion occurs when a frame instance is ready for transmission and has a priority higher then that of all instances of other frames currently in the tr
23. click a first time on the concerned table cell in order to select it and then you need to click a second time to enable editing Notice For the changes do be effective you need to hit Enter or move the focus to an other cell It is also possible to change the titles of offset VVCRT and relative load columns For this purpose right click on the column header and select Rename from the menu Offset ero Delete 0 Select All 0 5 Copy The column header becomes editable and you can enter the new name 02011 RTaW 30 49 NETCAR AnaLyzer V1 6 1 User ManuaL Offset My Offset DOA 0 0 0 0 Do not forget to push the enter button before you leave the column header otherwise the new name will be lost and replaced by the previous one Advice we recommend to keep the naming convention Offset xyz for offset columns so that the automatic naming of WCRT and relative load columns works 3 2 3 Deletion Columns that have been computed or generated such as worst case response times relative loads and offsets can be deleted by right clicking on the column title and by selecting the Delete entry in context menu WCRT SOA 4654 46 4 Select All 46 4 E Copy 46 4 Paste 46 4 ake ama Worst case scenario Advice At least one offset configuration must be defined otherwise a saved file will be corrupted and can not be opened correctly again Notice It is currently not poss
24. e Worst case scenario Reset Uttiet Reset all Offsets Lock all Offsets Unlock all Offsets The resulting lock icon indicates that the offset in the cell must be taken over as such by the optimization algorithm Random 1 0 105 420 15 Tip If almost all offset need to be locked you should first use the Lock all Offsets entry from the context menu of any of the cells of the offset configuration and then unlock individually those that may be changed In order to run the optimization select the Optimize Offsets entry from the Offsets menu Analysis Window Offsets DOA Offsets Shaping Offsets SQA Offsets Random This brings up the configuration dialog 2011 RTaW 45 49 NETCAR AnaLyzer V1 6 1 User ManuaL amp Offset local search optimization __ Na col x Offset local search range J Local Search Frame Selection Search criterion based on least pronty frame WCRT Search criterion based on the 10 least pronty frame WCRT Search criterion based on all the frames WERT Search criterion based on custom frames WERT EE i P m The Local Search Frame Selection section allows to specify for which frames the WCRT shall be decreased The WCRT of the other frames may increase After pushing the Start button the offset configuration selection dialog comes up if more then one offset configuration exists Offset selection Select wh
25. e order of their priorities when several frales have to be instantiated at a same notional moment then theoretically only one transmission buffer and a FIFO software queue would be enough to avoid inversion because new frames would only be instantiated when all pending frames have already been transmitted and because every batch of simultaneously waiting frames is ordered according to their priorities Notice that probably more than one transmission buffer would be needed to avoid the so called external priority inversions see 4 These kind of inversions occur when a controller has frames to send but is not fast enough to refill the transmission buffer and thus a frame may miss an arbitration in which it should have participated To be able to compute the worst case buffer utilizations the frame set must be present in the tool see Sections 3 2 and 3 3 on the different ways to achieve this In order to start the computation select the Buffer Utilization entry of the Analysis menu Analysis Windows Wert Wert Lower Bound Buffer Utilization Help Load Indicator Plot Before opening the menu make sure that the focus is on the window containing the frame set otherwise the menu entries will remain grayed out When several offset configuration are present a dialog opens up and asks for the offset configuration to use 2011 RTaW 40 49 NETCAR AnaLyzer V1 6 1 User ManuaAL When the compu
26. highest level of services for the products it develops Services include e Priority Technical Support by email phone or remote control software RTaW s technical support will respond within 1 or at most 2 business days Support is available in English French German or Italian e Maintenance RlaW will do its best to correct reproducible issues in its software as soon as possible and provide workaround solutions Besides RTaW is ready to implement and maintain customer specific versions 2011 RTaW 4 49 NETCAR AnaLyzer V1 6 1 User ManuaL e Data import export besides CSV and NETCAR Analyzer native format that are supported RlaW can provide DBC FIBEX or customer specific import export utilities e Advanced frame offset algorithms SOA and shaping algorithms to set offsets values offset optimization by local search algorithm Gateway support RTaW has an extensive experience in providing RGD services to companies developing systems for which performance and dependability matter Please refer to http www realtimeatwork com page_id 9 and to the technical papers that can be downloaded at http www realtimeatwork com page_id 5 for a good overview of what we are used to do Professional support and custom extensions available see our offer at url http www realtimeatwork com wp content uploads support NE I CAR Analyzer pdf 1 4 New releases and updates To be be kept updated with new releases and u
27. ible to delete ECUs or frames 3 3 Open or import of existing models In this section are described the various ways in which existing models can be opened or imported 3 3 1 Open menu entry The File menu contains an Open entry which allows to open NETCAR Analyzer files located anywhere on the computer 2011 RTaW 31 49 NETCAR AnaLyzer V1 6 1 User ManuaAL Regarder dans 92 e m T Tutorial landmark 0 xml ao Tutorial landrmark 1 xml Mes documents Tutorial landmark 2 xml recents 2 Tutoriallandmark 3 xrl Tutorial landmark 4 xml J LJ wW Tutorial landmark 5 xml L Eureau T EA E Mes documents LJ Poste de travail CG Mom du fichier T utorial landmark 1 sml e Favoris r seau Fichiers de type Fichiers xml E xml Annuler 3 3 2 Recent files menu entry The File menu contains a Recent Files entry which provides an easy access to recently opened files Edit Offsets J New Ctrl M E open Cri Analysis Windows Help Close Recent Files N Save Ctrl 5 CHWETCAR Analyzer Tutorial landmark 2 xml CNETCAR Analvzer Tutorial landmark 1 xml C NETCAR Analyzer Tuborial landmark xml C NETCAR Analyzer Tutorial landmark 4 xml 3 3 3 Import model from Csv file As its name says this kind of file contains Character Separated Values CSV but it is easier to understand as textual data under a tabular form as sh
28. ibute the Product without our prior written consent We reserve the right to withdraw any 2011 RTaW 3 49 NETCAR AnaLyzer V1 6 1 User ManuaL such consent or part thereof for any reason and without notice and to demand that you immediately cease any activity in respect of which permission is withdrawn You may NOT repackage translate adapt vary modify alter create derivative works based upon or integrate any other computer programs with the Product in whole or in part You may NOT use the Product to engage in or allow others to engage in any illegal activity You may NOT transfer or assign your rights or obligations under this Licence to any person or authorise all or any part of the Product to be copied on to another user s computer You may NOT decompile disassemble reverse engineer or otherwise attempt to discover the source code of the Product except to the extent that you may be expressly permitted to reverse engineer or decompile under applicable law 1 2 Installation Installer based distribution is available for Windows More information and the download links are available at url http www realtimeatwork com downloads 1 3 Support Free support is available through the forum at url http www realtimeatwork com forum For companies requiring guaranteed results RlaW is offering professional support customized developments training and R amp D services and is committed to providing the
29. ich offset should be used for this operation The selected offset configuration will be used as starting point for the optimization When the Ok button is pushed the optimization algorithm starts its work which may take several dozen of minutes 02011 RTaW 46 49 NETCAR AnaLyzer V1 6 1 User ManuaL Offsets Local Search Progress Improvement realized Local Search rea covered Improving offset of U4 frame When the optimization process has finished push the Done button A new column has been generated with the optimized offsets Its name is derived from the initial algorithm by appending 1 You may want to rename the column see Section 3 2 2 Modified offsets are displayed in green amp C NETCAR Analyzer Tutorial landmark 3_SOA xml Network Project BaudRate 500 Load 50 41 Granularity us 5000 EcuName Ecu 1 Ecu 2 Ecu 3 Ecu 4 Ecu 5 Ecu 6 Ecu 7 Ecu 8 Ecu 9 QueuePolicy ELE Frames WCRT SOA 4 674 4 594 4 304 1 784 3 424 2 764 3 364 4 634 4 574 4 634 4 504 3 304 4 634 4 634 4 464 1 014 1 514 4 474 3 654 3 674 2 804 2 494 0 934 4 264 3 384 Lower Bound of WCRT 2 924 2 844 2 824 1 554 2 134 1 864 2 134 2 924 2 864 2 924 2 924 2 114 2 924 2 924 2 924 1 014 1 244 2 804 2 324 2 134 2 114 1 764 0 934 2 784 2 134 SOA 2 34 2 30 0 86 8 92 34 24 5 53 3 36 0 46 2 29 0
30. inue with the resulting data set from the tutorial in Section 2 1 or open the corresponding file called Tutorial landmark 1 xml select the Load Indicator entry from the Analysis menu It is one of the major interest of verification tools such as NETCAR Analyzer to help the designer maximize the use of hardware resources With typical applicative level timing constraints in our experience 60 of bus load can be achieved if the network is well configured which in the first place involves using a tool like NETCAR Analyzer see ref pushing the limits 2011 RTaW 10 49 NETCAR AnaLyzer V1 6 1 User ManuaL Analysis Windows Help UI di WicrE Lower Bound Buffer Utilization Plot Gateway The result is an additional column that contains for each frame the relative load as defined above Rel Load Zero By clicking on the column header you can sort the lines so as to easily identify the highest values frames rel 219 BIH EA E 21 22 E AR ea pe pec e q q CT Wea i xml ee Network Frames Project powertrain 50 FrameName EcuName Frameld Period Length ie WERI Haoul e se jus E 10 0 7 074 70 74 frame59 10 0 5 744 57 44 frame34 10 0 4 494 AA od WS F ASA 40 5 0 15 774 39 44 EcuMame QueuePolicy frame82 Eu 6 409 40 0 14 014 35 04 a tenets femadelos e fume ase Ecu 1 Hof frame33 178 20 0 6 804 34 02 Eau 2 frame28 a 388 40 0 13 534 33 84 Ea frame
31. m fame35 Ewu l juos so a Juro 3a mes mim jo ao i frama tl Ema 1 w TAG nnr TENE 2011 RTaW 7 49 NETCAR AnaLyzer V1 6 1 User ManuaAL Let us now visualize graphically the computed WCRTs the analysis menu Analysis Windows Help wcrE Minimum Wert Buffer Utilization Load Indicator is select the Plot entry in select the Wert Zero series in the resulting plot configuration dialog and push the Ok button a DOI Select data to plot E E Too OT o The result should be the following 02011 RTaW Aas ordering Priority order 8 49 NETCAR AnaLyzer V1 6 1 User ManuaL ga NETCAR Analyzer Evaluation versi o File Edit Offsets Analysis Windows Help Jor WORT Zero 2 al E 40 50 Frame priority rank The Y range represents worst case frame response times in milliseconds A response time is the delay that spans from the moment when a frame is instantiated by the sending ECU and the moment where it is available in the reception buffers of the CAN controller of the receiving ECU In this graphic the response time range goes from Ums to 3Oms The X range represents the frames in order of their priorities It means for any couple of frames that the left one has a higher priority i e a smaller id than the right one If two frames are adjacent it means that there is no other frame with a priority in between The later does however not mean that
32. ng ECU Id Period Payload FrameNew1 Ecu O 100 40 7 FrameNewo Ecu 4 170 100 6 FrameNew3 Ecu 9 300 90 5 FrameNew4 Ecu_8 470 200 8 Go to the last line in the frame table and enter the properties of the frames frame Ecu 9 257 40 E d newFid T in order to obtain the following 2011 RTaW 25 49 NETCAR AnaLyzer V1 6 1 User ManuaAL Farto Eus jm o 5 o Jr Leave the offsets of the new frames to DO In order to get an idea of the worst impact of adding these new frames compute the worst case response times and plot them pie 8 WERT SOA Sw LYOM a 10 20 30 40 50 60 TO a0 90 100 Frame priority rank As can be seen adding the four new frames with zero offset make the worst case response time of some lower priority frame increase around Gms Now let us see if we can improve the situation by optimizing the offsets of the new frames For this purpose select the Optimize entry in the Offset menu Remember that this algorithm is only available if you have subscribed a professional Support contract 2011 RTaW 26 49 NETCAR AnaLyzer V1 6 1 User ManuaL E Offset local search optimization Offset local search range U Local Search Frame Selection 3 Search criterion based on least priority frame CRT Search criterion based on the 10 least priority frame CRT Search cnterion based on all the frames CAT 4 Search cntenon based on custom frames CA
33. nuaL usage Notice that it is a better indicator than the average bus load because it compares response times to deadlines Relative loads can only be computed after the WCRI have been computed see Section 3 4 1 on how to compute WCRTs Then select the Load Indicator entry of the Analysis menu Analysis Windows Help Wert Wert Lower Bound Buffer Utilization Load Indicator Before opening the menu make sure that the focus is on the window containing the frame set otherwise the menu entries will remain grayed out When several WCRT columns are present a dialog opens and asks for the one to use Offset selection Select which offset should be used for this operation Offset Random As a result a column appears containing the relative loads and with a title based on the name of the WCRT column with Rel Load as prefix instead of WCRT The name of the column can be changed see Section 3 2 2 In any case the name of the corresponding WCRT column can always be visualized in the tool tip of the column title simply move the mouse pointer over the column title and wait a second Rel Load Similar 744 lative Load 2 computed with WERT column E WCRKT Similar 20 3 4 3 Worst case transmission buffer utilization A hands on example is provided in Section 2 4 A CAN frame can only participate in the arbitration phase if it is located in a send buffer of a controller
34. o cu O E E Ecu 1 Ecu 2 la Ecu 3 Ecu 4 Ecu 5 Ecu b Ecu f Ecu 5 Ecu ho oo lts e The column Max Buffer shows the worst case number of waiting frames because of the Zero offsets configuration where at some time all frames are instantiated together critical instant the worst case number of waiting frames is simply equal to the number of different frames that may be send by the controller Computing the Buffer utilization for the SOA offsets configuration gives the following result if you see the Buffer Utilization menu entry grayed out make sure the frames window has the focus 2011 RTaW 18 49 NETCAR AnaLyzer V1 6 1 User ManuaL amp Maximum Buffer Utilization Phasl CAUsers S E ES Max BackLog 0 0 0 0 0 0 0 0 0 0 As can be seen the worst case number of waiting frames are much lower thanks to the transmission offsets that spread out the frame instantiation times It means for example that with the DOA offsets configuration 4 transmission buffers would be enough on ECU 1 for avoiding inner priority inversion when ever a frame Is instantiated at least one transmission buffer is free to stored it This strategy is quite simple to implement compared to other more sophisticated ones like the use of transmission cancellation The column Max Backlog represents the wors
35. own in Table 1 2011 RTaW 32 49 RTaW Sim Csv Format Bus Name Speed Frames Name frame 07 frame DU frame US frame U4 frame US frame UB frame 0O frame UB frame U9 frame 10 frame 117 frame 1 02011 RTaW NETCAR AnaLyzer V1 6 1 User ManuaL 1 0 body 125 Sending ECU ecuO ecuQ ecu ecu ecu ecud ecud ecud ecud ecud ecud ecud Table 1 Sample CSV import file shown as table Identifier 23 345 122 212 341 78 976 Je 36 6 af ae 107 Payload ONO O O A sa Oasis ON Period 100 1000 200 100 1000 200 100 1000 100 90 200 900 The format is the same as the one for importing frames into RlaW sim It allows to describe a CAN bus with connected ECUs and periodic Frames with transmission offsets Offset o0 120 o0 120 So 70 The character being used as separator the corresponding contents of the file is 33 49 NETCAR Anacyzer V1 6 1 User ManuaL Table 2 Sample CSV import file shown as text NETCAR Analyzer can not directly import the file You rather need to use an external tool able to transform the CSV file into an NETCAR Analyzer This tool is called Csv2Nca and located in the RTaW program folder in the Windows Start menu if you have installed it i R T a iit wi License ig Uninstall E Lab SeaMonkey Dbc Wea 1 1 0 Sun VirtualBox Guest Additions d Minplus Console 1
36. pdates subscribe to our eNewsletter at url http www realtimeatwork com subscribe 2 Quick start The goal of this section is to allow you to get quickly an idea about the kind of investigations NETCAR Analyzer allows to conduct The tutorials are based on the CAN High Speed example that has been used in 3 2 1 Compute worst case response times of CAN frames This is the main functionality of the NETCAR Analyzer tool and probably the most useful one because being able to compute worst case response times of CAN frames allows to validate latency constraints and to compare different configurations against each other in order to chose the most appropriate one To begin with the tutorial open the sample file that corresponds to Its start 2011 RTaW 9 49 NETCAR AnaLyzer V1 6 1 User ManuaL FA NETCAR Analyzer Evaluation File Edit Offsets Analy _ New Ctrl M EF Open Chrl c Close Recent Files Go to the samples tutorials folder and chose the file Tutorial landmark 0 xml NETCAR Analyzer Evaluation version not for production use Rod x File Edit Offsets Analysis Windows Help ge C Users jorn svn netcar Netcar Analyser docs help odt data Tutorial landmark 0 xml Network Frames Project powertrain50 Frame Name EcuName Frameld Period Length Diper fi 5 Load 50 41 san f 0 a elo j frame Granulariy us frame6 frame frame dt E ir E 2 8 8 B a f z
37. receiving ECUs If there is a hard latency constraint on the response times of a frame then the knowledge of the longest possible response time called worst case response time or WCRTI for short allows to verify if the constraint can always be met To be able to compute the WCRI of the frames the frame set must be present in the tool See Sections 3 2 and 3 3 on the different ways to achieve this In order to start the computation select the Wert entry of the Analysis menu Analysis Windows Help Minimum Wcert Buffer Utilization Load Indicator When several offset configurations are present a dialog opens and asks for the offset configuration to use Offset selection Select which offset should be used for this operation 2011 RTaW 37 49 NETCAR AnaLyzer V1 6 1 User ManuaL When the Ok button has been pushed the computation starts and a progress bar appears WICRT calculation of project pomertrainso Overall Progress Analyzing frames Cancel When the analysis is done a new column appears in the frame table for each frame it contains the WCRT induced by the selected offset configuration The name of that column ts by default based on the name of the offset configuration and has the prefix Wcrt The name of the column can be changed see Section 3 2 2 In any case the name of the corresponding offset configuration can always be visualized in the tool tip of the WCRT column title
38. t case number of frames still present in the transmission buffer s when the periodic COM task starts to look again for frames to instantiate Here we suppose that the period of the COM task is the greatest common divider of the offsets and periods in other words the largest period that allows to implement the transmission offsets with the help of a periodic task If that maximal backlog is zero then the following strategy for inner priority Inversion avoidance may be used if the periodic COM task instantiates frames in the order of their priority then theoretically only one transmission buffer and a software queue would be enough to avoid inversion because new frames would only be instantiated when all pending frames have already been transmitted Notice that probably more than one transmission buffer would be needed to avoid the so called external priority inversions see 4 These kind of inversions occur when a controller has frames to send but is not fast enough to refill the transmission buffer and thus a frame may miss an arbitration in which it should have participated 2011 RTaW 19 49 NETCAR AnaLyzer V1 6 1 User ManuaL 2 5 Optimize specific offsets NETCAR Analyzer provides algorithms for optimizing offsets according to WCRT based criteria Notice that this algorithm is only available if you have subscribed a professional Support contract The goal is to modify an existing offset configuration such that the WC
39. tation is done the following kind of window appears Max Butter Max BackLog q 3 C mo C CO A CO E CO a 3 5 Visualizing results as curves Columns that display WCRTs see Section 3 4 1 or relative loads see Section 3 4 2 can be plotted as curves For this purpose select the Plot entry from the Analysis Menu 2011 RTaw 41 49 NETCAR AnaLyzer V1 6 1 User ManuaL Analysis Windows Help Wert Wert Lower Bound Buffer Utilization Load Indicator Plot Before opening the menu make sure that the focus is on the window containing the frame set otherwise the menu entries will remain grayed out Then the dialog for selecting the data to be plotted appears The option X axis ordering allows to specify the meaning of the x axis e priority ordering the relative position of the frames in decreasing priority order is used as x coordinate priority value the value of the frame identifier is used as x coordinate Plotting Selection _ Select data to plot xais ordering WERT Zero W WERT SOA WCRT Random Lower Bound of WCRT Rel Load Zero E Reload SOA Pronty order After clicking on the Ok button the plot appears in a separate window 02011 RTaW 40 49 NETCAR AnaLyzer V1 6 1 User ManuaL ot CANETCAR Analyzer Tutorial landmark 4 SOM sm EE Ar WCRT Zero sd WCRT SOA uF WCRT Random Ar Lower Bound of WCRT sw
40. that typically enable doubling the bus load 1 which may defer the need for additional CAN networks and FlexRay technology NETCAR Analyzer feature list e Worst case response times jitters on CAN with and without frame offsets e Near optimal offsets assignment algorithms with user defined performance criteria e g optimize the worst case response times for a specific subset of tasks for instance the 10 lowest priority frames e Exhibit the situations leading to the worst case results can be checked by simulation e g with RTaWW Sim or testing e Enable dimensioning transmission reception buffers at the ECU and communication controller level e Handle both FIFO and prioritized waiting queues at the ECU level e Fast multi core implementation typically an exact response time computation requires less than 30 seconds for 100 frames on a dual core system 1 1 Licence of the software NETCAR Analyzer is copyrighted by INRIA INPL and RTaW It has been developed since 2005 first by INRIA and INPL then by RTaW since 2008 NETCAR Analyzer is free for all uses commercial training and research The software is provided as is without any express or implied warranty In no event shall INRIA INPL or RTaW be held liable for any damages arising from the use of the software In this Licence the Product means the software product NETCAR Analyzer You may NOT not resell charge for sub license rent lease loan or distr
41. thms provided by NETCAR Analyzer are the solution to this problem To be able to add new frames you must first make sure that no worst case response times or other computed columns are contained in the NETCAR Analyzer file You can for example make a copy of the file from previous tutorial steps and delete all computed columns see Section 3 2 3 for more details You may also simply open the file Tutorial landmark 5 xml which contains four additional frames with zero offsets and induced worst case response times This file has been created as follows open the file Tutorial landmark O xml from the 2011 RTaW 24 49 NETCAR AnaLyzer V1 6 1 User ManuaL samples tutorials folder see Section 2 1 as basis and regenerate the SOA offset configuration see Section 2 3 Once the Offset SOA column is created we suggest to delete the Offset Zero column because we do not need it any more right click on the column header to bring up the menu with the Delete entry Now we need to lock the existing offsets so that the optimization algorithm does not change them For this purpose right click into a cell of the Offset SOA column and select the Lock All Offsets entry Offset Similar Select All Copy Paste Lock Reset Offset Reset all Offsets Lock all OFFsets N Unlock all Offsets Now we are ready to add the following new frames Frame name Sendi
42. tional bus This apparent contradiction is due to the fact that frames must not just be transmitted but also within some bounded time The periodic load does however not take into account these constraints and is thus of limited use when an engineer wants to express how much transmission resource is already used or still free Let uS Suppose that the periods of the frames are also the deadlines for their transmission Since the worst case response times must be smaller than their deadlines for the constraints to be met it would be interesting to compare these with each other For this purpose NETCAR Analyzer provides the possibility to compute the relative load for a frame which is defined to be a fraction expressed in percent with the worst case response time as numerator and the corresponding period i e the deadline to meet as denominator A relative load value above 100 means that the deadline is missed in the worst case A relative load value of 50 means that the deadline is largely met even in the worst case but not only It also means that it is very likely that more higher priority frames may be added without causing any deadline to be missed because the WCRT is equal to the half of the period i e the deadline to meet Since relative loads are defined by frame it is useful to consider the maximum average etc and to plot them as a Curve In order to compute and visualize the relative loads for our example just cont
43. to cause deadline failures In Section 2 3 we show how worst case response times and thus relative loads can be reduced 2 3 Generate optimized offset configurations In this section we are going to generate an offset configuration in order to reduced the worst case response times computed in Section 2 1 for the Zero offset configuration This will also improve the relative loads computed in Section 2 2 To perform this tutorial either continue with the data resulting from the previous tutorials or open the file Tutorial landmark 2 xml from the samples tutorials folder Then go to the Offsets menu and select the All entry for the SOA algorithm 2011 RTaW 12 49 NETCAR AnaLyzer V1 6 1 User ManuaL Offsets Analysis Windows Help Offsets DOA Offsets Shaping Offsets Random Optimize Offsets Notice that the SOA algorithm is only available if you have subscribed a professional Support contract You may also use the DOA which produces less optimal offsets As a result of invoking the offset optimization algorithm a new column appears with the optimized offsets and named according to the used algorithm for example Offset SOA Before being able to compare this new offset configuration to the old one we need to compute the worst case response times chose the Wcert entry in the Analysis menu and then select Offset SOA name of the column that contains
44. uirements Note the result of the algorithms depends on the input order of frames which is equal to the display order when the algorithms are started The default display order groups the frames by sending ecu Sorting in increasing order of frame ids before starting the algorithms leads to different offsets which might produce different WCRTs 3 6 4 Optimization of specific WCRT A hands on example is provided in Sections 2 9 and 2 6 The tool provides a local search algorithm for optimizing the WCRTs of a subset of frames e while changing only certain offsets this algorithm is only available to users that have subscribed a professional Support contract The first aspect is interesting when the offset configuration algorithms lead to globally good WCRT but for certain frames the VWCRT should be smaller The second aspect is interesting in case of incremental design as illustrated in Section 2 6 Note the optimization algorithm does not change any existing offset configuration It uses an existing one as basis and creates a new one that take over some of the offsets whereas others are different If some offsets should not be changed you must first lock them For this purpose click into an offset cell then right click to bring up the context menu and select the Lock entry 2011 RTaW 44 49 NETCAR AnaLyzer V1 6 1 User ManuaL Offset Random WCRT Zero Rename Delete Select All Copy Past
45. us mer po o emo hm Ji asi ja oss ue o uz as po em am om as im a 10 45 6 77 30 r In order to evaluate this optimization you should compute the corresponding WCRTs see Section 2 1 and the relative loads See Section 2 2 and create the comparison plot with the initial DOA offsets dr WERT SOA l A WERT SOA sw LHIM 40 a0 Frame priority rank 2011 RTaW 23 49 NETCAR AnaLyzer V1 6 1 User ManuaL The comparison of the WCRT graphs shows that the WCRT of some lower priority frames including framelo and framebo2 have decreased at the cost of increasing the WCRTs of other frames which are mainly lower priority ones amp Plot C NETCAR Analyzer Tutorial landmark 3_SOA_LocalSearch xml o ie ese _ Analysis Ar Rel Load SOA A Rel Load SOA 1 peoT 13H 10 20 30 40 50 60 70 80 90 Frame priority rank 2 6 Incremental design When a new version of a product is created it frequently happens that as much as possible of an existing product should be reused For a frame set this means that new signals need to be added to existing frames or that new frames have to be added for new signals while leaving all other configuration parameters period id signal to frame allocation etc unchanged For the transmission offsets this means that good values need to be found for the new frames while keeping the offsets of the existing frames The optimization algori
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