From: Christoph Hellwig <hch@infradead.org>
To: Daniel Walker <dwalker@mvista.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Matthew Wilcox <matthew@wil.cx>,
linux-kernel@vger.kernel.org,
Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: Announce: Semaphore-Removal tree
Date: Sat, 26 Apr 2008 05:30:48 -0400 [thread overview]
Message-ID: <20080426093048.GA11443@infradead.org> (raw)
In-Reply-To: <1209158552.12461.53.camel@localhost.localdomain>
On Fri, Apr 25, 2008 at 02:22:31PM -0700, Daniel Walker wrote:
> If you can make a case for converting some semaphores to spinlocks be my
> guest .. If you have good reasoning I wouldn't stand in the way.. (Real
> time converts all the spinlocks to mutexes anyway ..)
Right at hand I have the XFS inode hash lock was converted from a rw_semaphore
to a rwlock_t becuase the context switch overhead was killing
performance in various benchmarks. This is a very typical scenary for
locks that are taken often and held for a rather short time. Add to
that fact that a spinlock is compltely optimized away for an UP kernel
while a mutex is not and the amount of memory that any mutex takes
compared to a spinlock you have a clear winner.
next prev parent reply other threads:[~2008-04-26 9:31 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-25 17:00 Matthew Wilcox
2008-04-25 20:24 ` Daniel Walker
2008-04-25 20:38 ` Daniel Walker
2008-04-25 21:12 ` Christoph Hellwig
2008-04-25 21:22 ` Daniel Walker
2008-04-26 9:30 ` Christoph Hellwig [this message]
2008-04-26 13:39 ` Peter Zijlstra
2008-04-26 13:44 ` Christoph Hellwig
2008-04-26 14:04 ` Peter Zijlstra
2008-04-28 4:59 ` David Chinner
2008-04-26 13:54 ` Stephen Rothwell
2008-04-26 15:59 ` Matthew Wilcox
2008-04-26 16:43 ` Stephen Rothwell
2008-04-28 5:10 ` David Chinner
2008-04-28 12:20 ` Matthew Wilcox
2008-04-29 0:09 ` David Chinner
2008-04-29 2:35 ` Matthew Wilcox
2008-04-29 3:56 ` David Chinner
2008-04-30 10:21 ` Matthew Wilcox
2008-04-30 10:06 ` Matthew Wilcox
2008-04-30 11:01 ` David Chinner
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