Date: Tue, 05 Dec 2000 09:52:42 -0700 From: Chuck Paterson <cp@bsdi.com> To: Jonathan Lemon <jlemon@flugsvamp.com> Cc: jhb@FreeBSD.org, smp@FreeBSD.org Subject: Re: Netgraph and SMP Message-ID: <200012051652.eB5Gqgm02018@berserker.bsdi.com> In-Reply-To: Your message of "Mon, 04 Dec 2000 17:48:40 CST." <200012042348.eB4NmeA73673@prism.flugsvamp.com>
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The vast majority of the cost of the lock manager locks is the mutex release and acquire. On Intel at least it is possible to have reader/write locks that are half as expensive in the non-contested cased. HOWEVER, we don't have these primitive now and reader writer locks with the lock manager are as cheap as we have got. We probably out to wrap the acquire and release in macros so we can swap them out later. Right now we just really need to get the functionality. I would also like to point out that the cost of all the atomic operations being put in the path collectively make the lock manager lock just not that big of a deal. This is not something I like, but just something to put things in perspective. Chuck } }Let's get realistic here. We're not going to get a shared lockmgr }lock for every stinking packet that comes into the network. While }SIX locks (or semaphore, or shared reader/writer) is nice in theory, }I think the performance impact is too much for this particular case. }-- }Jonathan } } }To Unsubscribe: send mail to majordomo@FreeBSD.org }with "unsubscribe freebsd-smp" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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