Date: Tue, 7 Aug 2001 02:19:54 -0500 From: Alfred Perlstein <bright@mu.org> To: Bosko Milekic <bmilekic@technokratis.com> Cc: Terry Lambert <tlambert2@mindspring.com>, Matt Dillon <dillon@earth.backplane.com>, Zhihui Zhang <zzhang@cs.binghamton.edu>, freebsd-hackers@FreeBSD.ORG Subject: Re: Allocate a page at interrupt time Message-ID: <20010807021954.Q85642@elvis.mu.org> In-Reply-To: <20010807031832.A46112@technokratis.com>; from bmilekic@technokratis.com on Tue, Aug 07, 2001 at 03:18:32AM -0400 References: <Pine.SOL.4.21.0108031432070.28997-100000@opal> <200108051955.f75Jtk882156@earth.backplane.com> <3B6F8A6C.B95966B7@mindspring.com> <20010807031832.A46112@technokratis.com>
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* Bosko Milekic <bmilekic@technokratis.com> [010807 02:16] wrote: > > On Mon, Aug 06, 2001 at 11:27:56PM -0700, Terry Lambert wrote: > > I keep wondering about the sagicity of running interrupts in > > threads... it still seems like an incredibly bad idea to me. > > > > I guess my major problem with this is that by running in > > threads, it's made it nearly impossibly to avoid receiver > > livelock situations, using any of the classical techniques > > (e.g. Mogul's work, etc.). > > References to published works? > > > It also has the unfortunate property of locking us into virtual > > wire mode, when in fact Microsoft demonstrated that wiring down > > interrupts to particular CPUs was good practice, in terms of > > assuring best performance. Specifically, running in virtual > > Can you point us at any concrete information that shows this? > Specifically, without being Microsoft biased (as is most "data" published by > Microsoft)? -- i.e. preferably third-party performance testing that attributes > wiring down of interrupts to particular CPUs as _the_ performance advantage. > > > wire mode means that all your CPUs get hit with the interrupt, > > whereas running with the interrupt bound to a particular CPU > > reduces the overall overhead. Even what we have today, with > > Obviously. > > > the big giant lock and redirecting interrupts to "the CPU in > > the kernel" is better than that... I really don't see what part of the current design specifically disallows one to both: 1) force interrupts to be taken on a particular cpu. 2) if that thread gets switched out, have it put on a per-cpu runqueue when it becomes runable preventing another cpu from snatching it up. I've already implemented #2, #1 requires touching hardware which isn't something I like doing. :) -- -Alfred Perlstein [alfred@freebsd.org] Ok, who wrote this damn function called '??'? And why do my programs keep crashing in it? To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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