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When a counter is 0 it may or may not be skipped. For uncore counters it is common they are only valid on 1 logical CPU and all other CPUs should be skipped. The PMU's cpumask was used for the skip calculation, but that cpumask may not reflect user overrides. Similarly a counter on a core PMU may explicitly not request a CPU be gathered. If the counter on this CPU's value is 0 then the counter should be skipped as it wasn't requested. Switch from using the PMU cpumask to that associated with the evsel to support these cases. Avoid potential crash with --per-thread mode where config->aggr_get_id is NULL. Add some examples for the tool event 0 counter skipping. Signed-off-by: Ian Rogers <irogers@google.com> Tested-by: Kan Liang <kan.liang@linux.intel.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Dominique Martinet <asmadeus@codewreck.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Clark <james.clark@linaro.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Leo Yan <leo.yan@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Weilin Wang <weilin.wang@intel.com> Cc: Yicong Yang <yangyicong@hisilicon.com> Link: https://lore.kernel.org/r/20250403194337.40202-3-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.