Date: Tue, 4 Jul 2006 12:32:30 +0100 (BST) From: Robert Watson <rwatson@FreeBSD.org> To: David Xu <davidxu@freebsd.org> Cc: freebsd-performance@freebsd.org Subject: Re: Updated fine-grain locking patch for UNIX domain sockets Message-ID: <20060704123124.S44010@fledge.watson.org> In-Reply-To: <20060703134429.P57091@fledge.watson.org> References: <20060630001142.Y67344@fledge.watson.org> <200607030837.04685.davidxu@freebsd.org> <20060703134429.P57091@fledge.watson.org>
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On Mon, 3 Jul 2006, Robert Watson wrote: > On Mon, 3 Jul 2006, David Xu wrote: > >> I found 5% performance decrease on dual P4, maybe P4 is quite bad when >> doing atomic operation. ;-) Thanks, > > When I've measured, generally, yes, P4 performance has been abysmal for > synchronization operations, both atomic operations and CPU-local interrupt > disabling, etc. > > I suspect rwlocks could use a bit of optimization in the contention case. > I've not dug into the code, so I'm not clear how they compare with respect > to adaptive behavior. I ran some micro-benchmarks, and rwlocks don't perform substantially differently from sleep mutexes for uncontended operation -- I've not measured cost under contention, however. Robert N M Watson Computer Laboratory University of Cambridge
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