mainlining shenanigans
89aafd67f2
After select_idle_sibling, p->recent_used_cpu is set to the new target. However on the next wakeup, prev will be the same as recent_used_cpu unless the load balancer has moved the task since the last wakeup. It still works, but is less efficient than it could be. This patch preserves recent_used_cpu for longer. The impact on SIS efficiency is tiny so the SIS statistic patches were used to track the hit rate for using recent_used_cpu. With perf bench pipe on a 2-socket Cascadelake machine, the hit rate went from 57.14% to 85.32%. For more intensive wakeup loads like hackbench, the hit rate is almost negligible but rose from 0.21% to 6.64%. For scaling loads like tbench, the hit rate goes from almost 0% to 25.42% overall. Broadly speaking, on tbench, the success rate is much higher for lower thread counts and drops to almost 0 as the workload scales to towards saturation. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210804115857.6253-2-mgorman@techsingularity.net |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| 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 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.