Messages in this thread |  | | | Date | Sun, 2 Jan 2011 09:57:55 +0100 | | From | Pavel Machek <> | | Subject | Re: [PATCH] Prevent users from disabling tickless |
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Hi!
> Disabling NO_HZ has a serious negative effect on performance -- an extra > 70us per I/O. Prevent users from deselecting it. > > Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
System with fixed HZ is really simpler etc... and 70us per i/o does not sound that bad.
Anyway, should not i/o overhead just be fixed? Pavel
> diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig > index f06a8a3..55b9a04 100644 > --- a/kernel/time/Kconfig > +++ b/kernel/time/Kconfig > @@ -5,13 +5,9 @@ config TICK_ONESHOT > bool > > config NO_HZ > - bool "Tickless System (Dynamic Ticks)" > + def_bool y > depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS > select TICK_ONESHOT > - help > - This option enables a tickless system: timer interrupts will > - only trigger on an as-needed basis both when the system is > - busy and when the system is idle. > > config HIGH_RES_TIMERS > bool "High Resolution Timer Support" >
-- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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