perf cpumap: Reduce cpu size from int to int16_t

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Fewer than 32k logical CPUs are currently supported by perf. A cpumap
is indexed by an integer (see perf_cpu_map__cpu) yielding a perf_cpu
that wraps a 4-byte int for the logical CPU - the wrapping is done
deliberately to avoid confusing a logical CPU with an index into a
cpumap. Using a 4-byte int within the perf_cpu is larger than required
so this patch reduces it to the 2-byte int16_t. For a cpumap
containing 16 entries this will reduce the array size from 64 to 32
bytes. For very large servers with lots of logical CPUs the size
savings will be greater.

Signed-off-by: Ian Rogers <irogers@google.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Link: https://lore.kernel.org/r/20250210191231.156294-1-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

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Ian Rogers 2025-02-10 11:12:31 -08:00 • committed by Namhyung Kim

parent 2337b7251d

commit c760174401

4 changed files with 54 additions and 27 deletions

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8

tools/lib/perf/cpumap.c

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3

tools/lib/perf/include/perf/cpumap.h

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66

tools/perf/util/cpumap.c

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2

tools/perf/util/env.c

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