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: Tue, 3 Jun 2008 13:15:34 -0700 (PDT) Message-ID: <20080603201534.BE46411D109@picon.linux-foundation.org> References: Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:53995 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755506AbYFCUQH (ORCPT ); Tue, 3 Jun 2008 16:16:07 -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 m53KFYN5009501 for ; Tue, 3 Jun 2008 13:15:35 -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=10846 ------- Comment #7 from anonymous@kernel-bugs.osdl.org 2008-06-03 13:15 ------- Reply-To: James.Bottomley@HansenPartnership.com On Tue, 2008-06-03 at 09:09 -0700, bugme-daemon@bugzilla.kernel.org wrote: > Should we consider, that such a difference is normal. You suggest that before > the kernel was dangerous at writing data? It's caching too much streaming data, yes. The danger is largely the amount of data you lose on a crash and mismanagement of the cache starving other applications. It's not that much of a problem. At an estimated write speed of ~70MB/s your 1GB of data is only around 15s to effect a full writeout. > So unpacking linux kernel (for example) is 5x times slower and it is not a > problem. That's just new way of caching data? We seldom see crashes (thanks to > linux) and we have power supply. There are many factors that could account for that. > I'd like testing on same hardware windows to see its behaviour and speed. > Anyway thanks for the clarifying of cache: write through. As you say, it was > not evident. > > So, now, what can we do to keep 2.6.21 behaviour? That's for a mail system > writing lots of little files and performance matters too. Well, initially, I'd try a benchmark that simulates the actual problem, like postmark. A streaming write tells you very little about the entire system performance under a mail server type load. James -- Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug, or are watching the assignee.