From: Matthew Wilcox <matthew@wil.cx>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>, linux-kernel@vger.kernel.org
Subject: [PATCH] Prevent users from disabling tickless
Date: Tue, 21 Dec 2010 16:39:43 -0700 [thread overview]
Message-ID: <20101221233942.GL1263@parisc-linux.org> (raw)
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>
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"
--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
next reply other threads:[~2010-12-21 23:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-21 23:39 Matthew Wilcox [this message]
2010-12-21 23:46 ` [PATCH] Prevent users from disabling tickless Rafael J. Wysocki
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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