Messages in this thread | | | Date | Sat, 11 Jun 2005 21:27:22 +0200 | From | Ingo Molnar <> | Subject | Re: PREEMPT_RT vs ADEOS: the numbers, part 1 |
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a couple of other wrokloads that are easy to measure and are useful for triggering worst-case latencies:
hackbench:
http://developer.osdl.org/craiger/hackbench/ http://developer.osdl.org/craiger/hackbench/src/hackbench.c
it creates tons of threads and does message-passing between them. E.g. "hackbench 50" or "hackbench 100" is a pretty good test.
i use 40 copies of LTP running in parallel:
while true; do ./runalltests.sh -x 40; done
this is good at triggering worst-case latencies too. Plus dbench is good too:
http://samba.org/ftp/tridge/dbench/ http://samba.org/ftp/tridge/dbench/dbench-3.03.tar.gz
# dbench-3.03> ./dbench 50 -c ./client.txt
also, there's a very good on-host IRQ-latency measurement tool as well:
http://www.affenbande.org/~tapas/wiki/index.php?rtc_wakeup
this uses TSC timestamping to detect wall-clock delays of the RTC interrupt. The tools jumps through lots of hoops to make sure the numbers are reliable. If you run it under the -RT kernel then run the RTC IRQ thread at a higher-than-all-other-threads priority:
chrt -f 95 -p `pidof 'IRQ 8'` ./rtc_wakeup -f 1024 -t 100000
(when you run it, and if you also have RTC_HISTOGRAM enabled in your .config, then the kernel will print a histogram when you stop rtc_wakeup, so you've got two sources of information.)
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