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| author | Johannes Weiner <hannes@cmpxchg.org> | 2019-02-02 01:21:15 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-02-02 02:46:24 +0300 |
| commit | 7b2489d37e1e355228f7c55724f77580e1dec22a (patch) | |
| tree | 51ae035f64cbed04a867484904466ca63e044e3a | |
| parent | e3df4c6e4836ce93cd5cf92d9cbdeaf4439a0241 (diff) | |
| download | linux-7b2489d37e1e355228f7c55724f77580e1dec22a.tar.xz | |
psi: clarify the Kconfig text for the default-disable option
The current help text caused some confusion in online forums about
whether or not to default-enable or default-disable psi in vendor
kernels. This is because it doesn't communicate the reason for why we
made this setting configurable in the first place: that the overhead is
non-zero in an artificial scheduler stress test.
Since this isn't representative of real workloads, and the effect was
not measurable in scheduler-heavy real world applications such as the
webservers and memcache installations at Facebook, it's fair to point
out that this is a pretty cautious option to select.
Link: http://lkml.kernel.org/r/20190129233617.16767-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | init/Kconfig | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/init/Kconfig b/init/Kconfig index 354146666d97..c9386a365eea 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -512,6 +512,17 @@ config PSI_DEFAULT_DISABLED per default but can be enabled through passing psi=1 on the kernel commandline during boot. + This feature adds some code to the task wakeup and sleep + paths of the scheduler. The overhead is too low to affect + common scheduling-intense workloads in practice (such as + webservers, memcache), but it does show up in artificial + scheduler stress tests, such as hackbench. + + If you are paranoid and not sure what the kernel will be + used for, say Y. + + Say N if unsure. + endmenu # "CPU/Task time and stats accounting" config CPU_ISOLATION |