Dmitry, The reason for the slowdown is that perf sched record default settings is tuned for x86 pretty much, and there's a huge amount of data being generated.
perf sched record is just a wrapper for perf record so try using this script for recording: > #!/bin/sh > perf record \ > -a \ > -R \ > -f \ > -m 8192 \ > -c 1 \ > -e sched:sched_switch \ > -e sched:sched_process_exit \ > -e sched:sched_process_fork \ > -e sched:sched_wakeup \ > -e sched:sched_migrate_task > You can verify that it works by looking at the amount of times that perf got woken up; typically is something like this > root@omap4430-panda:~# time ./perf-sched-record.sh > ^C[ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 0.031 MB perf.data (~1357 samples) ] > > > real 0m8.226s > user 0m0.016s > sys 0m0.641s > While running vanilla perf you get this: > root@omap4430-panda:~# time ./perf sched record > ^C[ perf record: Woken up 4 times to write data ] > [ perf record: Captured and wrote 11.678 MB perf.data (~510240 samples) ] > Processed 120671 events and lost 1 chunks! > > Check IO/CPU overload! > > > > real 0m11.039s > user 0m0.141s > sys 0m1.266s > That works for spr-replay just fine; might work for you as well. Regards -- Pantelis On Apr 4, 2012, at 1:13 PM, Dmitry Antipov wrote: > On 04/02/2012 02:18 PM, Pantelis Antoniou wrote: > >> Ah, about the load it's because perf sched record adds too many events to the >> recording (and configuring small buffers for perf). Using a smaller set >> of events works much better. > > I tried with a different subsets of 'sched:*' events, but it didn't help > too much - shell interactivity ruins to almost zero for everything beyond > 'perf sched record sleep 10'. > >> One thing I did was to record on /tmp - You have enough memory for this to >> work. > > Even with this, I can see a periodical noise about lost samples. It looks > like that perf subsystem is quite CPU-intensive even for the case where > the workload itself is just a thing like 'sleep 10'. > > Dmitry > _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
