2e9f9d4a72
Remove the "struct mutex lock" variable from annotation that is allocated per symbol. This removes in the region of 40 bytes per symbol allocation. Use a sharded mutex where the number of shards is set to the number of CPUs. Assuming good hashing of the annotation (done based on the pointer), this means in order to contend there needs to be more threads than CPUs, which is not currently true in any perf command. Were contention an issue it is straightforward to increase the number of shards in the mutex. On my Debian/glibc based machine, this reduces the size of struct annotation from 136 bytes to 96 bytes, or nearly 30%. Signed-off-by: Ian Rogers <irogers@google.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Andres Freund <andres@anarazel.de> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Yuan Can <yuancan@huawei.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Link: https://lore.kernel.org/r/20230615040715.2064350-2-irogers@google.com Signed-off-by: Namhyung Kim <namhyung@kernel.org>
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 Restructured Text 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.