From mboxrd@z Thu Jan 1 00:00:00 1970 From: bugme-daemon@bugzilla.kernel.org Subject: [Bug 10846] Slow write on LSISAS1068E (SAS6/iR) on kernel >= 2.6.22 Date: Mon, 2 Jun 2008 08:11:46 -0700 (PDT) Message-ID: <20080602151146.6F0CB11D108@picon.linux-foundation.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:40815 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750900AbYFBPMQ convert rfc822-to-8bit (ORCPT ); Mon, 2 Jun 2008 11:12:16 -0400 Received: from picon.linux-foundation.org (picon.linux-foundation.org [140.211.169.79]) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id m52FBkRG025915 for ; Mon, 2 Jun 2008 08:11:47 -0700 In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org http://bugzilla.kernel.org/show_bug.cgi?id=3D10846 ------- Comment #1 from anonymous@kernel-bugs.osdl.org 2008-06-02 08:1= 1 ------- Reply-To: James.Bottomley@HansenPartnership.com On Mon, 2008-06-02 at 07:57 -0700, bugme-daemon@bugzilla.kernel.org wrote: > Very easy: We also check for an untar of the kernel (5x slower) > debian-test:~# dd if=3D/dev/zero of=3D/root/test.cdrom bs=3D10k count= =3D60000 > 60000+0 enregistrements lus > 60000+0 enregistrements =C3=A9crits > 614400000 octets (614 MB) copi=C3=A9s, 1,17602 seconde, 522 MB/s > debian-test:~# uname -a > Linux debian-test.pr.univmed.fr 2.6.19.7 #1 SMP Fri May 30 15:55:50 > CEST 2008 > i686 GNU/Linux >=20 > debian:~# dd if=3D/dev/zero of=3Dtest.cdrom bs=3D10k count=3D60000 > 60000+0 records in > 60000+0 records out > 614400000 bytes (614 MB) copied, 7.51225 seconds, 81.8 MB/s > debian:~# uname -a > Linux debian 2.6.22-4-vserver-686 #1 SMP Tue Feb 12 22:02:04 UTC 2008 > i686 > GNU/Linux What exactly is test.cdrom on? A single disk? If so, then your first result is definitely bogus. The maximum bandwidth of a single SAS link is 300 MB/s, so it looks like the kernel is either caching the write or has timing issues. For a direct to platter speed, the data sheet for your drive gives 55-89MB/s, so I'd say 81.8 is well within the range. James --=20 Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=3Demail ------- You are receiving this mail because: ------- You are the assignee for the bug, or are watching the assignee. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html