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Peter Zijlstra 85e511df3c sched/eevdf: Allow shorter slices to wakeup-preempt
Part of the reason to have shorter slices is to improve
responsiveness. Allow shorter slices to preempt longer slices on
wakeup.

    Task                  |   Runtime ms  | Switches | Avg delay ms    | Max delay ms    | Sum delay ms     |

  100ms massive_intr 500us cyclictest NO_PREEMPT_SHORT

  1 massive_intr:(5)      | 846018.956 ms |   779188 | avg:   0.273 ms | max:  58.337 ms | sum:212545.245 ms |
  2 massive_intr:(5)      | 853450.693 ms |   792269 | avg:   0.275 ms | max:  71.193 ms | sum:218263.588 ms |
  3 massive_intr:(5)      | 843888.920 ms |   771456 | avg:   0.277 ms | max:  92.405 ms | sum:213353.221 ms |
  1 chromium-browse:(8)   |  53015.889 ms |   131766 | avg:   0.463 ms | max:  36.341 ms | sum:60959.230  ms |
  2 chromium-browse:(8)   |  53864.088 ms |   136962 | avg:   0.480 ms | max:  27.091 ms | sum:65687.681  ms |
  3 chromium-browse:(9)   |  53637.904 ms |   132637 | avg:   0.481 ms | max:  24.756 ms | sum:63781.673  ms |
  1 cyclictest:(5)        |  12615.604 ms |   639689 | avg:   0.471 ms | max:  32.272 ms | sum:301351.094 ms |
  2 cyclictest:(5)        |  12511.583 ms |   642578 | avg:   0.448 ms | max:  44.243 ms | sum:287632.830 ms |
  3 cyclictest:(5)        |  12545.867 ms |   635953 | avg:   0.475 ms | max:  25.530 ms | sum:302374.658 ms |

  100ms massive_intr 500us cyclictest PREEMPT_SHORT

  1 massive_intr:(5)      | 839843.919 ms |   837384 | avg:   0.264 ms | max:  74.366 ms | sum:221476.885 ms |
  2 massive_intr:(5)      | 852449.913 ms |   845086 | avg:   0.252 ms | max:  68.162 ms | sum:212595.968 ms |
  3 massive_intr:(5)      | 839180.725 ms |   836883 | avg:   0.266 ms | max:  69.742 ms | sum:222812.038 ms |
  1 chromium-browse:(11)  |  54591.481 ms |   138388 | avg:   0.458 ms | max:  35.427 ms | sum:63401.508  ms |
  2 chromium-browse:(8)   |  52034.541 ms |   132276 | avg:   0.436 ms | max:  31.826 ms | sum:57732.958  ms |
  3 chromium-browse:(8)   |  55231.771 ms |   141892 | avg:   0.469 ms | max:  27.607 ms | sum:66538.697  ms |
  1 cyclictest:(5)        |  13156.391 ms |   667412 | avg:   0.373 ms | max:  38.247 ms | sum:249174.502 ms |
  2 cyclictest:(5)        |  12688.939 ms |   665144 | avg:   0.374 ms | max:  33.548 ms | sum:248509.392 ms |
  3 cyclictest:(5)        |  13475.623 ms |   669110 | avg:   0.370 ms | max:  37.819 ms | sum:247673.390 ms |

As per the numbers the, this makes cyclictest (short slice) it's
max-delay more consistent and consistency drops the sum-delay. The
trade-off is that the massive_intr (long slice) gets more context
switches and a slight increase in sum-delay.

Chunxin contributed did_preempt_short() where a task that lost slice
protection from PREEMPT_SHORT gets rescheduled once it becomes
in-eligible.

[mike: numbers]
Co-Developed-by: Chunxin Zang <zangchunxin@lixiang.com>
Signed-off-by: Chunxin Zang <zangchunxin@lixiang.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Link: https://lkml.kernel.org/r/20240727105030.735459544@infradead.org
History 2024-08-17 11:06:45 +02:00
arch minmax: add a few more MIN_T/MAX_T users 2024-07-28 13:41:14 -07:00
block block: fix deadlock between sd_remove & sd_release 2024-07-24 09:51:21 -06:00
certs kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
crypto crypto: testmgr - generate power-of-2 lengths more often 2024-07-13 11:50:28 +12:00
Documentation CXL for v6.11 merge window 2024-07-28 09:33:28 -07:00
drivers minmax: add a few more MIN_T/MAX_T users 2024-07-28 13:41:14 -07:00
fs sched/rt: Rename realtime_{prio, task}() to rt_or_dl_{prio, task}() 2024-08-07 18:32:38 +02:00
include sched/fair: Avoid re-setting virtual deadline on 'migrations' 2024-08-17 11:06:45 +02:00
init Rust changes for v6.11 2024-07-27 13:44:54 -07:00
io_uring io_uring/napi: pass ktime to io_napi_adjust_timeout 2024-07-26 08:31:59 -06:00
ipc sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
kernel sched/eevdf: Allow shorter slices to wakeup-preempt 2024-08-17 11:06:45 +02:00
lib Rust changes for v6.11 2024-07-27 13:44:54 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm sched/rt: Rename realtime_{prio, task}() to rt_or_dl_{prio, task}() 2024-08-07 18:32:38 +02:00
net minmax: add a few more MIN_T/MAX_T users 2024-07-28 13:41:14 -07:00
rust Rust changes for v6.11 2024-07-27 13:44:54 -07:00
samples Driver core changes for 6.11-rc1 2024-07-25 10:42:22 -07:00
scripts Kbuild fixes for v6.11 2024-07-28 14:02:48 -07:00
security apparmor-pr-2024-07-24 PR 2024-07-25 2024-07-27 13:28:39 -07:00
sound Devicetree fixes for 6.11, part 1 2024-07-27 12:46:16 -07:00
tools turbostat release 2024.07.26 2024-07-28 10:52:15 -07:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt KVM generic changes for 6.11 2024-07-16 09:51:36 -04:00
.clang-format Docs: Move clang-format from process/ to dev-tools/ 2024-06-26 16:36:00 -06:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: add script and target to generate pacman package 2024-07-22 01:24:22 +09:00
.mailmap MAINTAINERS: mailmap: update James Clark's email address 2024-07-26 14:32:35 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS tracing: Update of MAINTAINERS and CREDITS file 2024-07-18 14:08:42 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS CXL for v6.11 merge window 2024-07-28 09:33:28 -07:00
Makefile Linux 6.11-rc1 2024-07-28 14:19:55 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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.