From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1KySpl-0001A4-Kp for qemu-devel@nongnu.org; Fri, 07 Nov 2008 10:01:13 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1KySpi-00019s-Ld for qemu-devel@nongnu.org; Fri, 07 Nov 2008 10:01:12 -0500 Received: from [199.232.76.173] (port=54998 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1KySpi-00019p-3F for qemu-devel@nongnu.org; Fri, 07 Nov 2008 10:01:10 -0500 Received: from ecfrec.frec.bull.fr ([129.183.4.8]:43836) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1KySph-0006l2-F7 for qemu-devel@nongnu.org; Fri, 07 Nov 2008 10:01:09 -0500 Received: from localhost (localhost [127.0.0.1]) by ecfrec.frec.bull.fr (Postfix) with ESMTP id 279261A18FD for ; Fri, 7 Nov 2008 16:01:04 +0100 (CET) Received: from ecfrec.frec.bull.fr ([127.0.0.1]) by localhost (ecfrec.frec.bull.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 17476-10 for ; Fri, 7 Nov 2008 16:01:01 +0100 (CET) Received: from cyclope.frec.bull.fr (cyclope.frec.bull.fr [129.183.4.9]) by ecfrec.frec.bull.fr (Postfix) with ESMTP id E7DA41A18F8 for ; Fri, 7 Nov 2008 16:01:00 +0100 (CET) Received: from [129.183.101.63] (frecb007144.frec.bull.fr [129.183.101.63]) by cyclope.frec.bull.fr (Postfix) with ESMTP id 3E77927289 for ; Fri, 7 Nov 2008 16:00:57 +0100 (CET) Subject: Re: [Qemu-devel] [PATCH 0/4] qcow2: Improve cluster refcount update From: Laurent Vivier In-Reply-To: <491449C4.4070500@codemonkey.ws> References: <1225990556.6576.10.camel@frecb07144> <49133D17.3050100@codemonkey.ws> <1226047453.4046.4.camel@frecb07144> <491449C4.4070500@codemonkey.ws> Content-Type: text/plain; charset=utf-8 Date: Fri, 07 Nov 2008 16:01:03 +0100 Message-Id: <1226070063.4046.56.camel@frecb07144> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Le vendredi 07 novembre 2008 =C3=A0 07:59 -0600, Anthony Liguori a =C3=A9= crit : > Laurent Vivier wrote: > > BTW, patch #1 is a clean-up (no change, only code move) and patch #2 > > doesn't align buffer, but try to minimise syscall (it improves > > performance with O_DSYNC too). > > > > Ignore patch #3 and #4 if you dislike them. > > =20 >=20 > But how useful is #1 and #2 if the buffers aren't aligned and we're=20 > hitting the slow path? In all cases #1 is totally useless as it is only cosmetic. #2 improves performance without aligned buffers and with "cache" set to default value. I've installed ubuntu 8.04 desktop on an empty qcow2 file using qemu: without patch: 16 minutes 54 seconds with patch: 15 minutes 44 seconds Regards, Laurent --=20 ------------------ Laurent.Vivier@bull.net ------------------ "Tout ce qui est impossible reste =C3=A0 accomplir" Jules Verne "Things are only impossible until they're not" Jean-Luc Picard