Date: Fri, 10 Nov 2000 02:32:23 +0900 From: Kenjiro Cho <kjc@csl.sony.co.jp> To: jlemon@flugsvamp.com Cc: smp@freebsd.org Subject: Re: SMP safe interface queues Message-ID: <20001110023223E.kjc@csl.sony.co.jp> In-Reply-To: <20001109092117.C72943@prism.flugsvamp.com> References: <20001108131343.A72943@prism.flugsvamp.com> <20001109121743Q.kjc@csl.sony.co.jp> <20001109092117.C72943@prism.flugsvamp.com>
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Jonathan Lemon wrote: > I understand that this is a problem for ALTQ. However, for my > purposes, making the interface queues SMP safe, it is not a problem. > The queueing discipline remains FIFO at this time, and each driver > instance has its own ifq. So the driver can safely peek at the > front of the queue, and place packets back using PREPEND() without > a problem. (assuming, of course, that the rx or tx routine of the > driver is single-threaded). > > I agree that moving forward it probably will be beneficial to hide > the internal queueing details, but it is not needed initially. How about calling IF_DRAIN() or IF_PREPEND() outside of the interrupt context? Although it might be unlikely in practice, the point is that a locking system needs the design of a self-contained operation model. (defined operations should work when the lock is properly held.) I doubt that it can be done without modifying the existing drivers. -Kenjiro To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the messagehome | help
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