Messages in this thread | | | Date | Sat, 03 Aug 2013 16:47:48 +0300 | From | Adrian Hunter <> | Subject | Re: [PATCH 1/9] perf tools: add test for reading object code |
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On 31/07/2013 8:43 p.m., Arnaldo Carvalho de Melo wrote: > Em Wed, Jul 31, 2013 at 12:11:13AM +0300, Adrian Hunter escreveu: >> On 29/07/2013 9:28 a.m., Namhyung Kim wrote: >>>> + >>>> +static int do_test_code_reading(void) >>>> +{ >>>> + struct machines machines; >>>> + struct machine *machine; >>>> + struct thread *thread; >>>> + struct perf_record_opts opts = { >>>> + .mmap_pages = UINT_MAX, >>>> + .user_freq = UINT_MAX, >>>> + .user_interval = ULLONG_MAX, >>>> + .freq = 40000, >>> >>> Is it intended to use the freq of 40000 instead of 4000 (default)? >> >> Yes. The "workload" is small so a higher sampling rate is preferable. > > But preferably one that is less than: > > [root@zoo ~]# cat /proc/sys/kernel/perf_event_max_sample_rate > 25000 > [root@zoo ~]# > > That is the reason why this test is failing on this Ivy Bridge notebook: > > [root@zoo ~]# dmesg | grep perf_event_max_sample_rate > [ 4068.969761] perf samples too long (2552> 2500), lowering kernel.perf_event_max_sample_rate to 50000 > [ 4069.842176] perf samples too long (5039> 5000), lowering kernel.perf_event_max_sample_rate to 25000 > [root@zoo ~]# > > Look at kernel/events/core.c. > > So keeping it at 4k may not be a bad idea, or at least have code that reads > /proc/sys/kernel/perf_event_max_sample_rate if using the highest freq is > desired.
I dropped it to 4k in V3.
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