From owner-freebsd-current@FreeBSD.ORG Fri Oct 11 21:52:11 2013 Return-Path: Delivered-To: current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id C61D2118; Fri, 11 Oct 2013 21:52:11 +0000 (UTC) (envelope-from jmg@h2.funkthat.com) Received: from h2.funkthat.com (gate2.funkthat.com [208.87.223.18]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 8A7C026C1; Fri, 11 Oct 2013 21:52:11 +0000 (UTC) Received: from h2.funkthat.com (localhost [127.0.0.1]) by h2.funkthat.com (8.14.3/8.14.3) with ESMTP id r9BLqAMA067462 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 11 Oct 2013 14:52:10 -0700 (PDT) (envelope-from jmg@h2.funkthat.com) Received: (from jmg@localhost) by h2.funkthat.com (8.14.3/8.14.3/Submit) id r9BLqAOs067461; Fri, 11 Oct 2013 14:52:10 -0700 (PDT) (envelope-from jmg) Date: Fri, 11 Oct 2013 14:52:10 -0700 From: John-Mark Gurney To: Maksim Yevmenkin Subject: Re: [rfc] small bioq patch Message-ID: <20131011215210.GY56872@funkthat.com> Mail-Followup-To: Maksim Yevmenkin , "current@freebsd.org" References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i X-Operating-System: FreeBSD 7.2-RELEASE i386 X-PGP-Fingerprint: 54BA 873B 6515 3F10 9E88 9322 9CB1 8F74 6D3F A396 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.2 (h2.funkthat.com [127.0.0.1]); Fri, 11 Oct 2013 14:52:10 -0700 (PDT) Cc: "current@freebsd.org" X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.14 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: Fri, 11 Oct 2013 21:52:11 -0000 Maksim Yevmenkin wrote this message on Fri, Oct 11, 2013 at 11:17 -0700: > i would like to submit the attached bioq patch for review and > comments. this is proof of concept. it helps with smoothing disk read > service times and arrear to eliminates outliers. please see attached > pictures (about a week worth of data) > > - c034 "control" unmodified system > - c044 patched system Can you describe how you got this data? Were you using the gstat code or some other code? Also, was your control system w/ the patch, but w/ the sysctl set to zero to possibly eliminate any code alignment issues? > graphs show max/avg disk read service times for both systems across 36 > spinning drives. both systems are relatively busy serving production > traffic (about 10 Gbps at peak). grey shaded areas on the graphs > represent time when systems are refreshing their content, i.e. disks > are both reading and writing at the same time. Can you describe why you think this change makes an improvement? Unless you're running 10k or 15k RPM drives, 128 seems like a large number.. as that's about halve number of IOPs that a normal HD handles in a second.. I assume you must be regularly seeing queue depths of 128+ for this code to make a difference, do you see that w/ gstat? Also, do you see a similar throughput of the system? -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."