From owner-cvs-all Fri Jul 12 15:46: 1 2002 Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5118B37B626; Fri, 12 Jul 2002 15:45:13 -0700 (PDT) Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id 107CF44A0A; Fri, 12 Jul 2002 15:36:46 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: from apollo.backplane.com (localhost [127.0.0.1]) by apollo.backplane.com (8.12.5/8.12.4) with ESMTP id g6CMLZLA063792; Fri, 12 Jul 2002 15:21:35 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.12.5/8.12.4/Submit) id g6CMLZwi063791; Fri, 12 Jul 2002 15:21:35 -0700 (PDT) (envelope-from dillon) Date: Fri, 12 Jul 2002 15:21:35 -0700 (PDT) From: Matthew Dillon Message-Id: <200207122221.g6CMLZwi063791@apollo.backplane.com> To: Alan Cox Cc: cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/kern kern_synch.c src/sys/sys proc.h src/sys/vm vm_zeroidle.c src/sys/i386/i386 genassym.c pmap.c References: <200207122017.g6CKH7fx096339@freefall.freebsd.org> <20020712205516.GD5265@cs.rice.edu> Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG :I think we should try to take this a step further. Specifically, we :should recognize when processors are running in user mode in order :to avoid IPIs on kernel pmap changes. On reentry to the kernel, :the processor would then do whatever is necessary to resync. If :too many kernel pmap changes accumulate, then you force a single :IPI that performs the changes in bulk. : :As a start, it would be interesting to know how many IPIs could be :avoided by such a scheme. : :Alan We need to run statistics to see where the IPIs are coming from. A deferral mechanism is only going to be more efficient if its simple and it might be better to instead just knock down the subsystems responsible for the majority of IPIs within the subsystem itself. -Matt Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message