Linux kernel source tree
a26b24b2e2
Freqency mode is the current default mode of Linux perf. A period of 1 is used as a starting period. The period is auto-adjusted on each tick or an overflow, to meet the frequency target. The start period of 1 is too low and may trigger some issues: - Many HWs do not support period 1 well. https://lore.kernel.org/lkml/875xs2oh69.ffs@tglx/ - For an event that occurs frequently, period 1 is too far away from the real period. Lots of samples are generated at the beginning. The distribution of samples may not be even. - A low starting period for frequently occurring events also challenges virtualization, which has a longer path to handle a PMI. The limit_period value only checks the minimum acceptable value for HW. It cannot be used to set the start period, because some events may need a very low period. The limit_period cannot be set too high. It doesn't help with the events that occur frequently. It's hard to find a universal starting period for all events. The idea implemented by this patch is to only give an estimate for the popular HW and HW cache events. For the rest of the events, start from the lowest possible recommended value. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20250117151913.3043942-3-kan.liang@linux.intel.com |
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| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .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.