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Commit 9e04139b authored by Johannes Weiner's avatar Johannes Weiner Committed by Suren Baghdasaryan
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UPSTREAM: 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: default avatarJohannes Weiner <hannes@cmpxchg.org>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>

(cherry picked from commit 7b2489d37e1e355228f7c55724f77580e1dec22a)

Bug: 127712811
Test: lmkd in PSI mode
Change-Id: I5d0cb901562fd74c82d9d211544745b802776d8a
Signed-off-by: default avatarSuren Baghdasaryan <surenb@google.com>
parent 2a070382

init/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -518,6 +518,17 @@ 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