From owner-svn-src-all@FreeBSD.ORG Thu Aug 15 20:35:30 2013 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 6A92D4C7 for ; Thu, 15 Aug 2013 20:35:30 +0000 (UTC) (envelope-from bounces+73574-8822-svn-src-all=freebsd.org@sendgrid.me) Received: from o3.shared.sendgrid.net (o3.shared.sendgrid.net [208.117.48.85]) by mx1.freebsd.org (Postfix) with SMTP id E54C52824 for ; Thu, 15 Aug 2013 20:35:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sendgrid.info; h=from :mime-version:to:cc:subject:references:in-reply-to:content-type :content-transfer-encoding; s=smtpapi; bh=KQuckAyVSUmDD8TDoqIKjO AE1/E=; b=NGyEA81IuzS1Tp+4VDcLnNX01DldnwgZ4GEV+0BxAruJvAHd5O5c+7 T/WzDuCSZ/gbuOPJJMMFNXwsgES/blwoSK1Rq7hwKn3ipg/sRXSNFiXhRvHm8k34 wojS8rDEJ1+5YomOJa/tUyEFB+0SM50v28fxddW7RbXhB4MLIsJBs= Received: by 10.42.83.83 with SMTP id filter-169.27486.520D3B90B Thu, 15 Aug 2013 20:35:28 +0000 (GMT) Received: from mail.tarsnap.com (unknown [10.60.208.13]) by mi22 (SG) with ESMTP id 14083b0aae3.6f75.8f33b9 for ; Thu, 15 Aug 2013 20:35:28 +0000 (UTC) Received: (qmail 32112 invoked from network); 15 Aug 2013 20:35:27 -0000 Received: from unknown (HELO clamshell.daemonology.net) (127.0.0.1) by ec2-107-20-205-189.compute-1.amazonaws.com with ESMTP; 15 Aug 2013 20:35:27 -0000 Received: (qmail 52355 invoked from network); 15 Aug 2013 20:32:24 -0000 Received: from unknown (HELO clamshell.daemonology.net) (127.0.0.1) by clamshell.daemonology.net with SMTP; 15 Aug 2013 20:32:24 -0000 Message-ID: <520D3AD8.4090207@freebsd.org> Date: Thu, 15 Aug 2013 13:32:24 -0700 From: Colin Percival User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:17.0) Gecko/20130722 Thunderbird/17.0.7 MIME-Version: 1.0 To: Ivan Voras Subject: Re: svn commit: r254380 - in head/sys: kern sys References: <201308152019.r7FKJI0H095440@svn.freebsd.org> In-Reply-To: X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SG-EID: A6W2xSVPHetogaU8rnzccWwgBYtN+QvIzXyjfe/10PFt7odERcTzFE6iBL5iSTO1m7sv21SKYZQTYn2G6njnecnA3U8KTYp9i76ZGpYhJ147i4zqw6b9YJDb+OV4eOUwUl1a8augvKIip6Ru0Iefhw== Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Aug 2013 20:35:30 -0000 On 08/15/13 13:29, Ivan Voras wrote: > On 15 August 2013 22:19, Colin Percival wrote: >> For workloads with R parallel reads and W parallel writes, this improves >> the time spent from O((R+W)^2) to O(W*(R+W)); i.e., heavy parallel-read >> workloads become significantly more scalable. >> >> No statistically significant change in buildworld time has been measured, >> but synthetic tests of parallel 'dd > /dev/null' and 'openssl enc >/dev/null' >> with the input file cached yield dramatic (up to 10x) improvement with high >> (up to 128 processes) levels of parallelism. > > That's interesting. Have you tried running the "blogbench" benchmark > before & after? No, I wasn't aware that it existed. Given that this change applies only to parallel operations *on the same vnode* and blogbench seems to have traffic randomly spread between many files, I doubt there would be any difference. -- Colin Percival Security Officer Emeritus, FreeBSD | The power to serve Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid