From owner-cvs-src@FreeBSD.ORG Mon Dec 5 22:31:52 2005 Return-Path: X-Original-To: cvs-src@freebsd.org Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id BE1D116A41F for ; Mon, 5 Dec 2005 22:31:52 +0000 (GMT) (envelope-from andre@freebsd.org) Received: from c00l3r.networx.ch (c00l3r.networx.ch [62.48.2.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id 8AE6143D9B for ; Mon, 5 Dec 2005 22:31:33 +0000 (GMT) (envelope-from andre@freebsd.org) Received: (qmail 13994 invoked from network); 5 Dec 2005 22:28:32 -0000 Received: from c00l3r.networx.ch (HELO freebsd.org) ([62.48.2.2]) (envelope-sender ) by c00l3r.networx.ch (qmail-ldap-1.03) with SMTP for ; 5 Dec 2005 22:28:32 -0000 Message-ID: <4394BFC6.E66F23A1@freebsd.org> Date: Mon, 05 Dec 2005 23:31:34 +0100 From: Andre Oppermann X-Mailer: Mozilla 4.8 [en] (Windows NT 5.0; U) X-Accept-Language: en MIME-Version: 1.0 To: John Baldwin References: <200512052045.jB5KjOQv050836@repoman.freebsd.org> <200512051552.47724.jhb@freebsd.org> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/kern subr_witness.c src/sys/sys _lock.h lock.h X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 Dec 2005 22:31:52 -0000 John Baldwin wrote: > > On Monday 05 December 2005 03:45 pm, John Baldwin wrote: > > jhb 2005-12-05 20:45:24 UTC > > > > FreeBSD src repository > > > > Modified files: > > sys/kern subr_witness.c > > sys/sys _lock.h lock.h > > Log: > > Tweak witness handling of lock object to shave 2 pointers off of each > > lock object (and thus off of each mutex and sx lock): > > > > ... > > > > With these changes, struct mtx shrinks from 36 to 28 bytes on 32-bit > > platforms and from 72 to 56 bytes on 64-bit platforms. Note that this > > commit will completely and utterly destroy the kernel ABI, so no MFC. > > > > Tested on: alpha, amd64, i386, sparc64 > > andre@ reported a 5% perf increase from this change on at least one network > benchmark. I tested only with WITNESS enabled and there it did in fact make a 5% difference on a HTTP connection performance test over the loopback interface. It is mostly limited by lock performance and I was measuring only 33 instructions on average between two lock operations (lock or unlock). -- Andre