Date: Wed, 27 Feb 2002 12:23:32 -0800 From: Alfred Perlstein <bright@mu.org> To: Julian Elischer <julian@elischer.org> Cc: Bosko Milekic <bmilekic@unixdaemons.com>, Terry Lambert <tlambert2@mindspring.com>, Jeff Roberson <jroberson@chesapeake.net>, arch@FreeBSD.ORG Subject: Re: Slab allocator Message-ID: <20020227202332.GU80761@elvis.mu.org> In-Reply-To: <Pine.BSF.4.21.0202271210460.97278-100000@InterJet.elischer.org> References: <20020227150519.A42681@unixdaemons.com> <Pine.BSF.4.21.0202271210460.97278-100000@InterJet.elischer.org>
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* Julian Elischer <julian@elischer.org> [020227 12:20] wrote: > > > On Wed, 27 Feb 2002, Bosko Milekic wrote: > > > > > On Wed, Feb 27, 2002 at 11:41:50AM -0800, Julian Elischer wrote: > > > The idea of Per CPU caches is that only that CPU is accessing it so > > > therefore you shouldn't need a lock at all. unless you are protecting > > > against interrupts on your own processor > > > and pre-emption. There are also ways to implement atomic > > > operations on queues that require no locks at all. > > > (e.g. using the test and swap instruction) > > > > Yes, that's exactly the point. You have to protect against pre-emption > > and interrupts. > maybe use a critical section instead.. > or better, a test/swap > or, both... > > but it sounds like you need the lock anyhow because > as you said.. it is possible a recently pre-empted thread may continue > to use the pool of it's old processor for a short moment, > (I'm not sure I like that idea) Leave it alone. The locks are a perfectly fine abstraction for the time being to get what we want and need. I'm for the per-cpu locks, and we can remove/fix them later if it's an issue. Removing locks is easier than adding them imo. -- -Alfred Perlstein [alfred@freebsd.org] 'Instead of asking why a piece of software is using "1970s technology," start asking why software is ignoring 30 years of accumulated wisdom.' Tax deductible donations for FreeBSD: http://www.freebsdfoundation.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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