Em Tue, Nov 12, 2013 at 05:40:39PM +0900, Namhyung Kim escreveu: > Hi Adrian, > > On Tue, 12 Nov 2013 09:07:36 +0200, Adrian Hunter wrote: > > On 11/11/13 22:22, Arnaldo Carvalho de Melo wrote: > >> From: Arnaldo Carvalho de Melo <a...@redhat.com> > >> > >> We were using it at 10 kHz, which doesn't work in machines where somehow > >> the max freq was auto reduced by the kernel: > >> > >> [root@ssdandy ~]# perf test 19 > >> 19: Test software clock events have valid period values : FAILED! > >> [root@ssdandy ~]# perf test -v 19 > >> 19: Test software clock events have valid period values : > >> --- start --- > >> Couldn't open evlist: Invalid argument > >> ---- end ---- > >> Test software clock events have valid period values: FAILED! > >> [root@ssdandy ~]# > >> > >> [root@ssdandy ~]# cat /proc/sys/kernel/perf_event_max_sample_rate > >> 7000 > >> > >> Reducing it to 500 Hz should be good enough for this test and also > >> shouldn't affect what it is testing. > >> > >> But warn the user if it fails, informing the knob and the freq tried. > > > > Doesn't work for me: > > > > ./perf test -v 19 > > 19: Test software clock events have valid period values : > > --- start --- > > mmap size 528384B > > mmap size 528384B > > All (0) samples have period value of 1! > > ---- end ---- > > Test software clock events have valid period values: FAILED! > > > > But this fixes it: > > > > diff --git a/tools/perf/tests/sw-clock.c b/tools/perf/tests/sw-clock.c > > index 93a7139..6664a7c 100644 > > --- a/tools/perf/tests/sw-clock.c > > +++ b/tools/perf/tests/sw-clock.c > > @@ -9,7 +9,7 @@ > > #include "util/cpumap.h" > > #include "util/thread_map.h" > > > > -#define NR_LOOPS 1000000 > > +#define NR_LOOPS 10000000 > > Or else, why not using the max_sample_rate as the freq value?
Sure, that probably is better, I was just trying the lazy way, as doing what you suggest entails reworking what Jiri did, since the routine that reads that max_sample_rate is not exported, needs some massaging, etc. Using a low enough max_sample_rate and warning the user that anyway would be better knowing that the sample rate lowered so dramatically looked quicker/lazy enough ;-) - Arnaldo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/