From owner-svn-src-head@FreeBSD.ORG Thu Aug 15 21:40:00 2013 Return-Path: Delivered-To: svn-src-head@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 64305B7E for ; Thu, 15 Aug 2013 21:40:00 +0000 (UTC) (envelope-from bounces+73574-9504-svn-src-head=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 C55F22B70 for ; Thu, 15 Aug 2013 21:39:59 +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=keEAWpDO7Ukl9Hx32n0GoR l0IQs=; b=kCs+vD64pOVQThSemgw/iEyvVlx6tTMBVZbDGtWsGYDUaRfEaT29Oj ARZ8tgpbppI6dAMO8orCNtLrB/yhggBfglU3azHQXzKBnVpSa9EMXiN+IIOp5QCu EFLciMfUbf2f2g/u7LWsu8Le4hP4bBpieUnboU1ltOEhY7f+2UDYM= Received: by with SMTP id filter-174.24601.520D4AA26 Thu, 15 Aug 2013 21:39:46 +0000 (GMT) Received: from mail.tarsnap.com (unknown [10.60.208.17]) by mi23 (SG) with ESMTP id 14083eb8b88.6931.6e5bf7 for ; Thu, 15 Aug 2013 21:39:46 +0000 (UTC) Received: (qmail 34087 invoked from network); 15 Aug 2013 21:39:45 -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 21:39:45 -0000 Received: (qmail 52803 invoked from network); 15 Aug 2013 21:36:43 -0000 Received: from unknown (HELO clamshell.daemonology.net) (127.0.0.1) by clamshell.daemonology.net with SMTP; 15 Aug 2013 21:36:43 -0000 Message-ID: <520D49EB.9060308@freebsd.org> Date: Thu, 15 Aug 2013 14:36:43 -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> <520D3AD8.4090207@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: EvYvoie/qnEezyq2t4eRKjDm9X7ZKbCMt75WvXA+XNFLOhoeet4uwWdrLLA4PF2CG2gJ9jguEOn7Gk0bgBfPv/FffnLSphQuSYT1VVOCYQOqUz1Q3dBGZqGGOMoraWU2GxIIjAWe+rWJFFBxQlcqqw== Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Aug 2013 21:40:00 -0000 On 08/15/13 14:34, Ivan Voras wrote: > On 15 August 2013 22:32, Colin Percival wrote: >> 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. > > Maybe it could help a bit on the directories? > > Whatever the problem may be (does FreeBSD still have single-writer + > multiple readers lock for processes accessing the same vnode?), there > is a huge difference in performance with blogbench between FreeBSD and > Linux. We have a single-writer / multiple-readers lock on *any particular byte* of a vnode. The rangelock code is what keeps track of this, and the locking contention I was reducing was in the rangelock bookkeeping. -- Colin Percival Security Officer Emeritus, FreeBSD | The power to serve Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid