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Date: Sat, 26 Apr 2008 05:30:48 -0400 From: Christoph Hellwig <hch@...radead.org> To: Daniel Walker <dwalker@...sta.com> Cc: Christoph Hellwig <hch@...radead.org>, Matthew Wilcox <matthew@....cx>, linux-kernel@...r.kernel.org, Stephen Rothwell <sfr@...b.auug.org.au> Subject: Re: Announce: Semaphore-Removal tree 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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