Re: [PATCHSET 0/8] perf tools: Do not set attr.exclude_guest by default (v4)

[Liang, Kan]

On 2024-09-30 8:20 p.m., Namhyung Kim wrote:
> Hello,
> 
> I found perf tools set exclude_guest bit inconsistently.  It used to
> set the bit but now the default event for perf record doesn't.  So I'm
> wondering why we want the bit in the first place.
> 
> Actually it's not good for PMUs don't support any exclusion like AMD
> IBS because it disables new features after the exclude_guest due to
> the missing feature detection logic.
> 
> v4 changes)
> 
>  * handle EOPNOTSUPP error in compatible way  (Kan)
>  * drop --exclude-guest option in perf stat
>  * not to separate exclude_hv fallback
>  * rename to exclude_GH_default  (Kan)
>  * drop the RFC from the subject
> 
> v3) https://lore.kernel.org/lkml/20240905202426.2690105-1-namhyung@xxxxxxxxxx/
> 
>  * move exclude_guest fallback to the front
>  * fix precise_max handling on AMD
>  * simplify the default event for perf record
> 
> v2) https://lore.kernel.org/lkml/20240904064131.2377873-1-namhyung@xxxxxxxxxx/
> 
>  * update the missing feature detection logic
>  * separate exclude_hv fallback
>  * add new fallback for exclude_guest
> 
> v1) https://lore.kernel.org/lkml/20240902014621.2002343-1-namhyung@xxxxxxxxxx/
> 
> AFAIK it doesn't matter for the most cases but perf kvm.  If users
> need to set the bit, they can still use :H modifier.  For vPMU pass-
> through or Apple M1, it'd add the exclude_guest during the fallback
> logic.
> 
> Also the kernel feature detection logic should be separated from the
> exclude bit tests since it depends on the PMU implementation rather
> than the core kernel features.  So I changed it to use a software
> event for the detection and factor out some hw-specific checks.
> 
> The code is available at 'perf/exclude-v4' branch in
> git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git
> 
> Thanks,
> Namhyung
> 
> 
> Namhyung Kim (8):
>   perf tools: Add fallback for exclude_guest
>   perf tools: Don't set attr.exclude_guest by default
>   perf tools: Simplify evsel__add_modifier()
>   perf tools: Do not set exclude_guest for precise_ip
>   perf tools: Detect missing kernel features properly
>   perf tools: Move x86__is_amd_cpu() to util/env.c
>   perf tools: Check fallback error and order
>   perf record: Just use "cycles:P" as the default event
> 

The patch set looks good to me.

Acked-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>

Thanks,
Kan

>  tools/perf/arch/x86/util/Build              |   1 -
>  tools/perf/arch/x86/util/env.c              |  19 -
>  tools/perf/arch/x86/util/env.h              |   7 -
>  tools/perf/arch/x86/util/pmu.c              |   2 +-
>  tools/perf/builtin-kvm.c                    |   1 +
>  tools/perf/builtin-record.c                 |   4 +-
>  tools/perf/builtin-stat.c                   |  18 +-
>  tools/perf/dlfilters/dlfilter-test-api-v0.c |   2 +-
>  tools/perf/dlfilters/dlfilter-test-api-v2.c |   2 +-
>  tools/perf/tests/attr/test-record-dummy-C0  |   2 +-
>  tools/perf/tests/parse-events.c             |  30 +-
>  tools/perf/util/env.c                       |  24 ++
>  tools/perf/util/env.h                       |   4 +
>  tools/perf/util/evsel.c                     | 394 ++++++++++++++------
>  tools/perf/util/evsel.h                     |   1 -
>  tools/perf/util/parse-events.c              |   6 +-
>  tools/perf/util/util.c                      |  10 +-
>  tools/perf/util/util.h                      |   3 +
>  18 files changed, 364 insertions(+), 166 deletions(-)
>  delete mode 100644 tools/perf/arch/x86/util/env.c
>  delete mode 100644 tools/perf/arch/x86/util/env.h
>