VME in CMS

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1 Introduction 2 VME64x in CMS 3 VMEBridges     3.1 CAEN         3.1.1 Technical Info         3.1.2 Status         3.1.3 Software         3.1.4 Firmware         3.1.5 Measurements     3.2 SBS

Performance Measurements The VME Hardware was a optical VME bridge from CAEN (V2718_Kit) and a RAMix139 VME memory (32Mb). The PC was a PIII 800 MHz PC running Linux with a 2.4.x kernel. The measurements have been carried out with CAEN library libCAENVME.so.2.1 firmware for V2718 : v1718vub_rev0.11.rbf firmware for A2818 : a2818pcb_rev0.5.rbf firmware for A2719 : a2719ci_rev0.3.rbf All measurements used the HAL library(version ver-03-05-test-04). A measurement with the usb version of the CAEN Bridge (Model V2718_Kit) cane be looked at here. (The measurement has been obtained with the firmware v1718vub_rev0.12.rbf for the V1718 board. The rest of the measurement conditions have been identical to those for the optical bridge.) Performance for single accesses This test was made running the "PerformanceTester" application contained in the HAL examples. It has been run one time with the dummy BusAdapter and one time with the BusAdapter for the VME Bridge. This allows to subtract the overhead due to the HAL library itself. Results using the VMEDummyBusAdapter =============================================================================== ATTENTION ==> the measured time values do not measure the process time but the total time elapsed during the measurement (laboratory-time) So, in order to get meaningfull measurements, be sure not to have other active processes on your machine. =============================================================================== (TimeoutException) Timeout during polling the item "rwFlagMask" 1000ms have passed wheras the timeout has been set to 1000ms 3680000 polls have been carried out (HardwareDevice::pollItem) read r/w-item with full mask : 2.57833us read r/w-item with full mask and offset : 2.95839us write r/w-item with full mask : 2.99179us write r/w-item with full mask and offset : 3.42508us read r-item with full mask : 2.53569us read r-item with full mask and offset : 2.91862us write w-item with full mask : 2.66218us write w-item with full mask and offset: 3.07601us unmaskedRead r/w-item with full mask : 2.66056us unmaskedRead r/w-item with full mask and offset : 2.90977us unmaskedWrite r/w-item with full mask : 2.65765us unmaskedWrite r/w-item with full mask and offset : 2.92356us setBit r/w-item with 1bit mask : 3.26963us setBit r/w-item with 1bit mask and offset : 3.71627us resetBit r/w-item with 1bit mask : 3.26833us resetBit r/w-item with 1bit mask and offset : 3.69591us setBit w-item with 1bit mask : 2.95803us setBit w-item with 1bit mask and offset : 3.35657us resetBit w-item with 1bit mask : 2.85544us resetBit w-item with 1bit mask and offset : 3.37863us =============================================================================== Results using the CAEN2718LinuxPCIBusAdapter Remark: The items which need significant more time involve two VME accesses. (This is documented in the HAL documentation). In order to obtain the overhead due to the driver and the hardware the measured values of the values above measured with the DummyBusadapter must be subtracted from the values below. =============================================================================== ATTENTION ==> the measured time values do not measure the process time but the total time elapsed during the measurement (laboratory-time) So, in order to get meaningfull measurements, be sure not to have other active processes on your machine. =============================================================================== (TimeoutException) Timeout during polling the item "rwFlagMask" 1009ms have passed wheras the timeout has been set to 1000ms 100000 polls have been carried out (HardwareDevice::pollItem) read r/w-item with full mask : 14.2928us read r/w-item with full mask and offset : 14.7548us write r/w-item with full mask : 24.1194us write r/w-item with full mask and offset : 24.6097us read r-item with full mask : 14.1733us read r-item with full mask and offset : 14.7672us write w-item with full mask : 13.5404us write w-item with full mask and offset: 14.0083us unmaskedRead r/w-item with full mask : 14.1884us unmaskedRead r/w-item with full mask and offset : 14.8598us unmaskedWrite r/w-item with full mask : 13.7226us unmaskedWrite r/w-item with full mask and offset : 14.3353us setBit r/w-item with 1bit mask : 24.3967us setBit r/w-item with 1bit mask and offset : 24.9829us resetBit r/w-item with 1bit mask : 24.3639us resetBit r/w-item with 1bit mask and offset : 24.9634us setBit w-item with 1bit mask : 14.0308us setBit w-item with 1bit mask and offset : 14.5417us resetBit w-item with 1bit mask : 13.821us resetBit w-item with 1bit mask and offset : 14.4us =============================================================================== Performance for Block Transfers Measurement conditions: The measurements exclusively measure the block transfer performance of the VME bridge. Data blocks have been transferred for different sizes from the host via the VME Bridge to the memory module and vice versa. The data has been generated with a random generator. The size of the data blocks has been varied from 256 bytes to 32Mb. Altogether 12 blocksizes where chosen. The data read back was always verified against the data previously written. No data error has been observed. The measurement at each data point was repeated 100 times. The mean values of the resulting transfer rates are summarized in the colored plot below. Additional plots have been produced, in order to show the distribution of the data throughput for the 100 measurements taken for at each block-size. Results Read and write performance as a function of the block size. Distribution of read throughput for fixed block sizes (100 Measurements). Distribution of write throughput for fixed block sizes (100 Measurements).

last changed: 2012-10-02 comments to: Christoph Schwick