From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Matthew Wilcox <matthew@wil.cx>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Arjan van de Ven <arjan@infradead.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Prevent users from disabling tickless
Date: Wed, 22 Dec 2010 00:46:23 +0100 [thread overview]
Message-ID: <201012220046.23759.rjw@sisk.pl> (raw)
In-Reply-To: <20101221233942.GL1263@parisc-linux.org>
On Wednesday, December 22, 2010, Matthew Wilcox wrote:
>
> 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>
OTOH, it causes some systems to not work at all still. Sadly.
Thanks,
Rafael
> 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"
>
>
next prev parent reply other threads:[~2010-12-21 23:47 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-21 23:39 Matthew Wilcox
2010-12-21 23:46 ` Rafael J. Wysocki [this message]
2010-12-22 0:24 ` Matthew Wilcox
2010-12-22 0:38 ` Rafael J. Wysocki
2010-12-22 21:00 ` Frank Rowand
2010-12-22 21:34 ` Matthew Wilcox
2010-12-22 22:32 ` Frank Rowand
2010-12-26 22:22 ` Len Brown
2010-12-26 23:20 ` Grant Coady
2010-12-26 23:23 ` Regarding kernel work queue issues Raj Kumar
2010-12-25 15:42 ` [PATCH] Prevent users from disabling tickless Stefan Richter
2011-01-02 8:57 ` Pavel Machek
2011-01-02 9:15 ` Eric Dumazet
2011-01-02 10:59 ` Serge Belyshev
2011-01-02 11:06 ` Remy Bohmer
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