From owner-freebsd-hackers Sun Aug 9 00:15:14 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id AAA20635 for freebsd-hackers-outgoing; Sun, 9 Aug 1998 00:15:14 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from allegro.lemis.com (allegro.lemis.com [192.109.197.134]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id AAA20630 for ; Sun, 9 Aug 1998 00:15:10 -0700 (PDT) (envelope-from grog@freebie.lemis.com) Received: from freebie.lemis.com (freebie.lemis.com [192.109.197.137]) by allegro.lemis.com (8.9.1/8.9.0) with ESMTP id QAA06259; Sun, 9 Aug 1998 16:44:44 +0930 (CST) Received: (from grog@localhost) by freebie.lemis.com (8.9.1/8.9.0) id QAA11299; Sun, 9 Aug 1998 16:44:37 +0930 (CST) Message-ID: <19980809164437.C11095@freebie.lemis.com> Date: Sun, 9 Aug 1998 16:44:37 +0930 From: Greg Lehey To: dg@root.com Cc: John Baldwin , FreeBSD Hackers Subject: Re: AMD-specific kernel code (was: How long a wait?) References: <19980809160829.A11214@freebie.lemis.com> <199808090649.XAA23702@implode.root.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.91.1i In-Reply-To: <199808090649.XAA23702@implode.root.com>; from David Greenman on Sat, Aug 08, 1998 at 11:49:51PM -0700 WWW-Home-Page: http://www.lemis.com/~grog Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Saturday, 8 August 1998 at 23:49:51 -0700, David Greenman wrote: >> The effect on CPU performance is also noticable: here are "make >> world" times: >> >> Without write allocate: >> >> real 106m58.441s >> user 63m0.960s >> sys 20m25.035s >> >> With write allocate: >> >> real 114m16.402s >> user 69m41.733s >> sys 17m54.862s >> >> These were only a rough test (I had other stuff running at the same >> time), but in practice this normally only makes about 1 minute >> difference. I'd guess that the difference *is* real. Obviously there >> must be a reason for enabling or disabling this behaviour, and I'd >> guess that write allocation is most effective when one process is >> using much CPU time. 'make world' starts thousands of short-lived >> process, and may thus be the worst-case scenario. In this connection, >> it's also interesting to note that system time was down and user time >> was up with write allocation. >> >> I have patches available. Does anybody want to commit them? > > Based on the above performance numbers, I'd say no - they appear to be > a pessimization. If they were always like that, I'd agree. But as I said, I think it depends on the application, and I'm prepared to believe that long-running servers could benefit significantly. Still, that's not proven. I've put the patches on ftp://ftp.lemis.com/pub/AMD-write-allocate-patch. They relate to today's -CURRENT. How about some other people grabbing them and trying them out? Greg -- See complete headers for address and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message