From owner-freebsd-current@FreeBSD.ORG Mon Jul 6 09:39:30 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E5FFB106566C for ; Mon, 6 Jul 2009 09:39:30 +0000 (UTC) (envelope-from raj@semihalf.com) Received: from smtp.semihalf.com (smtp.semihalf.com [213.17.239.109]) by mx1.freebsd.org (Postfix) with ESMTP id 90CE88FC12 for ; Mon, 6 Jul 2009 09:39:30 +0000 (UTC) (envelope-from raj@semihalf.com) Received: from [10.0.0.34] (cardhu.semihalf.com [213.17.239.108]) by smtp.semihalf.com (Postfix) with ESMTPSA id 31B14C4021; Mon, 6 Jul 2009 11:19:24 +0200 (CEST) Message-Id: From: Rafal Jaworowski To: Kostik Belousov In-Reply-To: <20090703082040.GN2884@deviant.kiev.zoral.com.ua> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Apple Message framework v935.3) Date: Mon, 6 Jul 2009 11:20:30 +0200 References: <200907030204.51415.max@love2party.net> <20090703082040.GN2884@deviant.kiev.zoral.com.ua> X-Mailer: Apple Mail (2.935.3) Cc: Max Laier , freebsd-current@freebsd.org, Jeff Roberson Subject: Re: MD5 test slowdown X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 06 Jul 2009 09:39:31 -0000 On 2009-07-03, at 10:20, Kostik Belousov wrote: > On Fri, Jul 03, 2009 at 02:04:50AM +0200, Max Laier wrote: >> On Thursday 02 July 2009 13:32:08 Rafal Jaworowski wrote: >>> I'm observing some heavy slowdown seen with md5 test on PowerPC: >>> >>> 1. On the MPC8572 machine with today's HEAD I'm getting: >>> >>> # md5 -t >>> MD5 time trial. Digesting 100000 10000-byte blocks ... done >>> Digest = 766a2bb5d24bddae466c572bcabca3ee >>> Time = 36.930565 seconds >>> Speed = 27077842.000000 bytes/second >>> >>> 2. While a couple of months back it yielded 6x shorter times on this >>> very same hardware, like this one: >>> >>> # md5 -t >>> MD5 time trial. Digesting 100000 10000-byte blocks ... done >>> Digest = 766a2bb5d24bddae466c572bcabca3ee >>> Time = 6.027277 seconds >>> Speed = 165912400.000000 bytes/second >>> >>> Timers work fine, the slowdown is real. I don't know if this is >>> PowerPC related, and was wondering if anybody observed something >>> similar on other archs perhaps? Any suggestions what could be >>> causing >>> this or where to look? I cannot see immediate suspects in the arch/ >>> platform code. >> >> "signifanctly slowdown of FreeBSD 8.0-CURRENT/amd64" to this >> mailing list >> reports something that might be related. It seems there is a patch >> available, but not committed yet. Though I'm not sure about the >> nature of >> the problem exactly. Jeff? > > I want to make some points clear to avoid a confusion and spread of > FUD. > It seems we have at least three issues, all different: > 1. Syscalls slowdown on amd64. To see this, you need to microbenchmark > syscall enter/leave sequence. I doubt that it can be seen on any > load except while (1) {getpid();} loops or such. The issue is valid > _only_ for amd64. > I developed the patch with the input from Jeff who confirmed that > this slowdown is solved by the change. > 2. There are enough independent reports of i/o slowdown to believe > that > some problem is real; but we have not seen numbers or detailed > configurations or (most desirable) the revision after which the > slowdown started. Note the i/o part. > > This report is for PPC (right ?) and for workload that is purely > CPU-bounded. After additional testing my slowdown looks more like a PowerPC (E500 only) issue: nwhitehorn@ checked his G4 (AIM) system and could not observe this, so it seems something local to E500. Rafal