From owner-freebsd-smp Thu May 2 7:25:42 2002 Delivered-To: freebsd-smp@freebsd.org Received: from 12-234-96-171.client.attbi.com (12-234-96-171.client.attbi.com [12.234.96.171]) by hub.freebsd.org (Postfix) with ESMTP id F187A37B417; Thu, 2 May 2002 07:25:34 -0700 (PDT) Received: by 12-234-96-171.client.attbi.com (Postfix, from userid 1000) id 1817BA900; Thu, 2 May 2002 07:29:49 -0700 (PDT) Date: Thu, 2 May 2002 07:29:49 -0700 From: Jonathan Mini To: John Baldwin Cc: freebsd-smp@FreeBSD.org, Andrew Gallatin Subject: Re: hlt when idle? Message-ID: <20020502072949.C56560@stylus.haikugeek.com> References: <20020501151123.G30080@stylus.haikugeek.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: ; from jhb@FreeBSD.org on Thu, May 02, 2002 at 10:16:31AM -0400 Sender: owner-freebsd-smp@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org 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 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