From owner-freebsd-hackers@FreeBSD.ORG Sun Jul 22 16:15:31 2012 Return-Path: Delivered-To: hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id B021C106566C; Sun, 22 Jul 2012 16:15:31 +0000 (UTC) (envelope-from bryanv@daemoninthecloset.org) Received: from torment.daemoninthecloset.org (torment.daemoninthecloset.org [94.242.209.234]) by mx1.freebsd.org (Postfix) with ESMTP id 6DE6D8FC16; Sun, 22 Jul 2012 16:15:31 +0000 (UTC) X-Virus-Scanned: amavisd-new at daemoninthecloset.org Received: from sage.daemoninthecloset.org (sage.daemoninthecloset.org [127.0.1.1]) by sage.daemoninthecloset.org (Postfix) with ESMTP id C3073D2CC; Sun, 22 Jul 2012 11:08:37 -0500 (CDT) Date: Sun, 22 Jul 2012 11:08:37 -0500 (CDT) From: Bryan Venteicher To: Dieter BSD Message-ID: <738102528.760.1342973317543.JavaMail.root@sage.daemoninthecloset.org> In-Reply-To: <20120722061933.298410@gmx.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [10.51.1.6] X-Mailer: Zimbra 7.1.4_GA_2555 (ZimbraWebClient - GC18 (Linux)/7.1.4_GA_2555) Cc: hackers@freebsd.org, current@freebsd.org Subject: Re: Awful FreeBSD 9 block IO performance in KVM X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 22 Jul 2012 16:15:31 -0000 ----- Original Message ----- > From: "Dieter BSD" > To: hackers@freebsd.org, current@freebsd.org > Sent: Sunday, July 22, 2012 1:19:32 AM > Subject: Re: Awful FreeBSD 9 block IO performance in KVM > > >>> da0: 3.300MB/s transfers > >>> da0: Command Queueing enabled > > > > root@freebsd:/root # dd if=/dev/zero of=/dev/da1 bs=16384 > > count=262144 > > > > 4294967296 bytes transferred in 615.840721 secs (6974153 bytes/sec) > > 1) Does a larger block size (bs=1m) help? > > 2) That's roughly the speed I'd expect without queueing. Is it really > making effective use of queueing, or is something limiting queueing to > one transfer at a time? The likely fix here is basically do vtblk_startio() in a separate kproc that vtblk_strategy() enqueues bio's to. This has been on my todo for a while, but haven't had the time. Also, the use of bioq_disksort() probably doesn't gain much for virtualized disks, but I never found much of a difference in my testing. > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to > "freebsd-hackers-unsubscribe@freebsd.org" >