From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: thomas.falcon@intel.com
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Namhyung Kim <namhyung@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Kan Liang <kan.liang@linux.intel.com>,
linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
Andi Kleen <ak@linux.intel.com>,
Dapeng Mi <dapeng1.mi@linux.intel.com>
Subject: Re: [Patch v3 0/2] perf record: ratio-to-prev event term for auto counter reload
Date: Fri, 3 Oct 2025 16:27:55 -0300 [thread overview]
Message-ID: <aOAju-lDNHBFnYWx@x1> (raw)
In-Reply-To: <20251002234308.64218-1-thomas.falcon@intel.com>
On Thu, Oct 02, 2025 at 06:43:04PM -0500, thomas.falcon@intel.com wrote:
> The goal is to limit event sampling to cases when the branch miss rate
> exceeds 20%. If the branch instructions sample period is exceeded
> first, both events are reloaded. If branch misses exceed their
> threshold first, only the second counter is reloaded, and a sample is
> taken.
> To simplify this, provide a new “ratio-to-prev” event term
> that works alongside the period event option or -c option.
> This would allow users to specify the desired relative rate
> between events as a ratio, making configuration more intuitive.
> With this enhancement, the equivalent command would be:
>
> perf record -e "{cpu_atom/branch-misses/ppu,\
> cpu_atom/branch-instructions,period=1000000,ratio_to_prev=5/u}" \
> -- ./mispredict
> or
> perf record -e "{cpu_atom/branch-misses/ppu,\
> cpu_atom/branch-instructions,ratio-to-prev=5/u}" -c 1000000 \
> -- ./mispredict
> [1] https://lore.kernel.org/lkml/20250327195217.2683619-1-kan.liang@linux.intel.com/
> v3: rebase to current perf-tools-next
Thanks, applied to perf-tools-next,
- Arnaldo
> v2: (changes below suggested by Ian Rogers):
next prev parent reply other threads:[~2025-10-03 19:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-02 23:43 [Patch v3 0/2] perf record: ratio-to-prev event term for auto counter reload thomas.falcon
2025-10-02 23:43 ` [Patch v3 1/2] perf record: Add ratio-to-prev term thomas.falcon
2025-10-07 8:55 ` Namhyung Kim
2025-10-08 20:30 ` Falcon, Thomas
2025-10-02 23:43 ` [Patch v3 2/2] perf record: Add auto counter reload parse and regression tests thomas.falcon
2025-10-03 19:27 ` Arnaldo Carvalho de Melo [this message]
2025-10-06 16:23 ` [Patch v3 0/2] perf record: ratio-to-prev event term for auto counter reload Falcon, Thomas
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