linux-kernel - Re: [PATCHSET 0/8] perf tools: Do not set attr.exclude

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Message-ID: <8a20f55b-ebfd-4171-9677-399f6c6f4257@amd.com>
Date: Tue, 15 Oct 2024 09:55:04 +0530
From: Ravi Bangoria <ravi.bangoria@....com>
To: Namhyung Kim <namhyung@...nel.org>,
 Arnaldo Carvalho de Melo <acme@...nel.org>, Ian Rogers <irogers@...gle.com>,
 Kan Liang <kan.liang@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...nel.org>, Adrian Hunter <adrian.hunter@...el.com>,
 Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...nel.org>,
 LKML <linux-kernel@...r.kernel.org>, linux-perf-users@...r.kernel.org,
 Mark Rutland <mark.rutland@....com>, James Clark <james.clark@....com>,
 Kajol Jain <kjain@...ux.ibm.com>, Thomas Richter <tmricht@...ux.ibm.com>,
 Atish Patra <atishp@...shpatra.org>, Palmer Dabbelt <palmer@...osinc.com>,
 Mingwei Zhang <mizhang@...gle.com>, Ravi Bangoria <ravi.bangoria@....com>
Subject: Re: [PATCHSET 0/8] perf tools: Do not set attr.exclude_guest by
 default (v4)

On 01-Oct-24 5:50 AM, 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@kernel.org/
> 
>  * 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@kernel.org/
> 
>  * 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@kernel.org/
> 
> 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

Apart from few minor things, series looks good to me:

Reviewed-by: Ravi Bangoria <ravi.bangoria@....com>

Thanks,
Ravi