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7b6dd7a923
Perf event names aren't case sensitive. For sysfs events the entire directory of events is read then iterated comparing names in a case insensitive way, most often to see if an event is present. Consider: $ perf stat -e inst_retired.any true The event inst_retired.any may be present in any PMU, so every PMU's sysfs events are loaded and then searched with strcasecmp to see if any match. This event is only present on the cpu PMU as a JSON event so a lot of events were loaded from sysfs unnecessarily just to prove an event didn't exist there. This change avoids loading all the events by assuming sysfs event names are always either lower or uppercase. It uses file exists and only loads the events when the desired event is present. For the example above, the number of openat calls measured by 'perf trace' on a tigerlake laptop goes from 325 down to 255. The reduction will be larger for machines with many PMUs, particularly replicated uncore PMUs. Ensure pmu_aliases_parse() is called before all uses of the aliases list, but remove some "pmu->sysfs_aliases_loaded" tests as they are now part of the function. Reviewed-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Ian Rogers <irogers@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Clark <james.clark@arm.com> Cc: Jing Zhang <renyu.zj@linux.alibaba.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Ravi Bangoria <ravi.bangoria@amd.com> Cc: Thomas Richter <tmricht@linux.ibm.com> Link: https://lore.kernel.org/r/20240502213507.2339733-7-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.