From: David Laight <David.Laight@ACULAB.COM>
To: 'Ian Rogers' <irogers@google.com>, Leo Yan <leo.yan@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Kan Liang <kan.liang@linux.intel.com>,
James Clark <james.clark@linaro.org>,
Kyle Meyer <kyle.meyer@hpe.com>, Ben Gainey <ben.gainey@arm.com>,
"linux-perf-users@vger.kernel.org"
<linux-perf-users@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v1 1/8] perf: Increase MAX_NR_CPUS to 4096
Date: Mon, 9 Dec 2024 21:35:52 +0000 [thread overview]
Message-ID: <74f3444d28044d858f0f696cea6485a8@AcuMS.aculab.com> (raw)
In-Reply-To: <CAP-5=fXOE3k9bmYOykpN6M9bBwLqP54MWWMGxutJ4SS2G_3MZQ@mail.gmail.com>
..
> > > Just changing the int to be a s16 would lower the memory overhead,
> > > which is why I'd kind of like the abstraction to be minimal.
> >
> > Here I am not clear what for "changing the int to be a s16". Could you
> > elaberate a bit for this?
>
> I meant this :-)
> https://lore.kernel.org/lkml/20241207052133.102829-1-irogers@google.com/
How many time is this allocated?
If it is 2 bytes in a larger structure it is likely to be noise.
For a local the code is likely to be worse.
Any maths and you start forcing the compiler to mask the value
(on pretty much anything except x86).
David
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next prev parent reply other threads:[~2024-12-09 21:36 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-06 4:40 [PATCH v1 0/8] Cpumap improvements for large MAX_NR_CPUS Ian Rogers
2024-12-06 4:40 ` [PATCH v1 1/8] perf: Increase MAX_NR_CPUS to 4096 Ian Rogers
2024-12-06 10:24 ` Leo Yan
2024-12-06 16:25 ` Ian Rogers
2024-12-06 23:03 ` Leo Yan
2024-12-07 5:24 ` Ian Rogers
2024-12-09 21:35 ` David Laight [this message]
2024-12-09 21:47 ` Ian Rogers
2024-12-06 4:40 ` [PATCH v1 2/8] perf cpumap: Reduce transitive dependencies on libperf MAX_NR_CPUS Ian Rogers
2024-12-06 4:40 ` [PATCH v1 3/8] libperf cpumap: Hide/reduce scope of MAX_NR_CPUS Ian Rogers
2024-12-06 4:40 ` [PATCH v1 4/8] libperf cpumap: Be tolerant of newline at the end of a cpumask Ian Rogers
2024-12-06 4:40 ` [PATCH v1 5/8] perf pmu: Remove use of perf_cpu_map__read Ian Rogers
2024-12-06 4:40 ` [PATCH v1 6/8] libperf cpumap: " Ian Rogers
2024-12-06 4:40 ` [PATCH v1 7/8] libperf cpumap: Remove perf_cpu_map__read Ian Rogers
2024-12-06 4:40 ` [PATCH v1 8/8] libperf cpumap: Grow array of read CPUs in smaller increments Ian Rogers
2024-12-06 23:03 ` [PATCH v1 0/8] Cpumap improvements for large MAX_NR_CPUS Leo Yan
2024-12-09 16:04 ` Arnaldo Carvalho de Melo
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