Messages in this thread | | | From | Vince Weaver <> | Date | Fri, 20 Apr 2018 12:51:12 -0400 (EDT) | Subject | Re: [RFC] perf/core: what is exclude_idle supposed to do |
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On Fri, 20 Apr 2018, Vince Weaver wrote:
> > AFAICT it works on Power and possibly ARM. > > at least some ARMs are a bit more honest about it than x86 > > ivybridge: > Performance counter stats for '/bin/ls': > 1,368,162 instructions > 1,368,162 instructions:I > > pi2/ARM cortex-A7 > Performance counter stats for '/bin/ls': > 1,910,083 instructions > <not supported> instructions:I > > I'd fire up my Power8 machine to see but not sure it's worth the hassle > and/or having to get out the ear protection.
I did power up the Power8 machine in the end:
power8: perf stat -e cycles,cycles:I sleep 5 Performance counter stats for 'sleep 5': 14,271,273 cycles 14,271,273 cycles:I
???
But then if I try again on power8
perf stat -a -e cycles,cycles:I sleep 5 Performance counter stats for 'system wide': 1,238,772,322,327 cycles 1,238,674,771,713 cycles:I
there is a difference.
But then on ivybridge
perf stat -a -e cycles,cycles:I sleep 5 Performance counter stats for 'system wide': 589,598,104 cycles 589,537,190 cycles:I
there is also a different in system wide mode.
So maybe exclude_idle does do something on x86? Or am I completely misunderstanding what the flag is supposed to be indicating?
Vince
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