Date: Thu, 2 May 2002 07:29:49 -0700 From: Jonathan Mini <mini@FreeBSD.org> To: John Baldwin <jhb@FreeBSD.org> Cc: freebsd-smp@FreeBSD.org, Andrew Gallatin <gallatin@cs.duke.edu> Subject: Re: hlt when idle? Message-ID: <20020502072949.C56560@stylus.haikugeek.com> In-Reply-To: <XFMail.20020502101631.jhb@FreeBSD.org>; from jhb@FreeBSD.org on Thu, May 02, 2002 at 10:16:31AM -0400 References: <20020501151123.G30080@stylus.haikugeek.com> <XFMail.20020502101631.jhb@FreeBSD.org>
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John Baldwin [jhb@FreeBSD.org] wrote : > > On 01-May-2002 Jonathan Mini wrote: > > Andrew Gallatin [gallatin@cs.duke.edu] wrote : > >> > No, the interrupts seem to be round-robin, but each clock intr is only > >> > sent to one CPU unlike on alpha where they are broadcast. > >> > >> So each CPU gets (1/num_cpu) * hz clock interrupts/sec? > > > > Yes, but because the timer is set to num_cpu*hz, each CPU ends up getting > > the normal hz interrupts. That's why it runs round-robin but looks like a > > broadcast. > > Eh, are you talking about the Alpha? On x86 we don't do this and have to use > IPI's to simulate a broadcast-type deal. > I am obviously thinking about some other SMP implementation, but I have no idea which one. Somebody, somewhere, sets the routing of the clock interrupt to be delivered in a round-robin fashion, and then multiplies the clock frequency by the number of processors. They're really proud of this solution, because (they claim) it reduces contentions of clock-triggered events across processors. Maybe it was Sun? -- Jonathan Mini <mini@freebsd.org> http://www.haikugeek.com "He who is not aware of his ignorance will be only misled by his knowledge." -- Richard Whatley To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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