Re: [PATCH] perf, tools: Fall weak group back even for EBADF

From: Jiri Olsa
Date: Wed Sep 06 2017 - 07:52:26 EST


On Tue, Sep 05, 2017 at 02:13:24PM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
>
> It's not possible to run a package event and a per cpu event in
> the same group. This is used by some of the power metrics.
> They work correctly when not using a group.
>
> Normally weak groups should handle that, but in this case EBADF
> is returned instead of the normal EINVAL.
>
> strace -e perf_event_open ./perf stat -v -e '{cstate_pkg/c2-residency/,msr/tsc/}:W' -a sleep 1
> Using CPUID GenuineIntel-6-3E
> perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, PERF_FLAG_FD_CLOEXEC) = -1 EINVAL (Invalid argument)
> perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, 0) = -1 EINVAL (Invalid argument)
> perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, 0) = -1 EINVAL (Invalid argument)
> perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, 0) = -1 EINVAL (Invalid argument)
> perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, 0) = 3
> perf_event_open({type=0x7 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, 3, 0) = 4
> perf_event_open({type=0x7 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 1, 0, 0) = -1 EBADF (Bad file descriptor)
>
> and perf errors out.
>
> Make weak groups trigger a fall back for EBADF too. Then this case works correctly:
>
> $ ./perf stat -v -e '{cstate_pkg/c2-residency/,msr/tsc/}:W' -a sleep 1
> Using CPUID GenuineIntel-6-3E
> Weak group for cstate_pkg/c2-residency//2 failed
> cstate_pkg/c2-residency/: 476709882 1000598460 1000598460
> msr/tsc/: 39625837911 12007369110 12007369110
>
> Performance counter stats for 'system wide':
>
> 476,709,882 cstate_pkg/c2-residency/
> 39,625,837,911 msr/tsc/
>
> 1.000697588 seconds time elapsed
>
> This fixes perf stat -M Power ...
>
> $ ./perf stat -M Power --metric-only -a sleep 1
>
> Performance counter stats for 'system wide':
>
> Turbo_Utilization C3_Core_Residency C6_Core_Residency C7_Core_Residency C2_Pkg_Residency C3_Pkg_Residency C6_Pkg_Residency C7_Pkg_Residency
> 1.0 0.7 30.0 0.0 0.9 0.1 0.4 0.0
>
> 1.001240740 seconds time elapsed
>
> Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

seems ok me

Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>

thanks,
jirka