From owner-freebsd-smp Mon May 8 12: 8:54 2000 Delivered-To: freebsd-smp@freebsd.org Received: from thehousleys.net (frenchknot.ne.mediaone.net [24.147.224.201]) by hub.freebsd.org (Postfix) with ESMTP id 3C46337B923 for ; Mon, 8 May 2000 12:08:51 -0700 (PDT) (envelope-from jim@thehousleys.net) Received: from thehousleys.net (baby.int.thehousleys.net [192.168.0.24]) by thehousleys.net (8.9.3/8.9.3) with ESMTP id PAA50455; Mon, 8 May 2000 15:08:28 -0400 (EDT) Message-ID: <391710AB.B6C680AC@thehousleys.net> Date: Mon, 08 May 2000 15:08:27 -0400 From: James Housley Organization: The Housleys dot Net X-Mailer: Mozilla 4.72 [en] (X11; U; FreeBSD 3.4-STABLE i386) X-Accept-Language: en MIME-Version: 1.0 To: Matthew Dillon Cc: Terry Lambert , Jeremiah Gowdy , Steve Passe , freebsd-smp@FreeBSD.ORG Subject: Re: hlt instructions and temperature issues References: <200004282108.OAA01313@usr08.primenet.com> <200004282240.PAA14200@apollo.backplane.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-smp@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Matthew Dillon wrote: > I like the HLT + IPI idea, but none of the patches to date really cover > the bases and switching performance is not going to be as good as when you > don't have the HLT due to the overhead of sending the IPIs and having to > keep track of which cpu's are in a HLT'd state and which are not (so you > don't send IPI's to all cpu's gratuitously). > > This is not a trivial problem because we cannot afford to have N cpu's > all trying to do locked bitset instructions on the same memory location > in order to go idle -- that alone will create big latencies. Just a thought after reading this thread. Might it make sense to implement a simple form of this or a similar scheme for the dual-processor system? There would only be 1 processor accessing the lock-memory location. Dual processor systems are leaving the server only areana and entering user/power-user areana. Then work on a more elegant solution the 4-way and above, I know i skipped the 3-way. Jim -- "...there's no idea that's so good you can't ruin it with a few well-placed idiots." -- Charles Spickman To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message