Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755969AbYFAXoA (ORCPT ); Sun, 1 Jun 2008 19:44:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752694AbYFAXnw (ORCPT ); Sun, 1 Jun 2008 19:43:52 -0400 Received: from lucidpixels.com ([75.144.35.66]:50169 "EHLO lucidpixels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752662AbYFAXnv (ORCPT ); Sun, 1 Jun 2008 19:43:51 -0400 Date: Sun, 1 Jun 2008 19:43:49 -0400 (EDT) From: Justin Piszcz To: Daniel J Blueman cc: Linux Kernel Subject: Re: Limits of the 965 chipset & 3 PCI-e cards/southbridge? ~774MiB/s peak for read, ~650MiB/s peak for write? In-Reply-To: <6278d2220806011423o22e98f27qfd72fbd152d19d9f@mail.gmail.com> Message-ID: References: <6278d2220806011423o22e98f27qfd72fbd152d19d9f@mail.gmail.com> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1868 Lines: 48 On Sun, 1 Jun 2008, Daniel J Blueman wrote: > On 1 Jun, 10:50, Justin Piszcz wrote: >> I have 12 enterprise-class seagate 1TiB disks on a 965 desktop board and >> it appears I have hit the limit, if I were able to get the maximum speed >> of all drives, ~70MiB/avg * 12 = 840MiB/s but it seems to stop aound 774 >> MiB/s (currently running badblocks on all drives).. > > Nice test. The Seagate 7200.11 drives deliver 120MB/s (outer zone, > raw) each, and there is an issue with CFQ dispatching requests; see: > > http://groups.google.co.uk/group/linux.kernel/browse_thread/thread/b88264b084a2dfe0/a1bc0f67837bad00 > > A quick workaround tweak is: > > # echo 0 >/sys/block/sda/queue/iosched/slice_idle > > Does this help any? This gives the difference of ~68MB/s vs ~120MB/s > on my 7200.11 ;-) . > > That said, the i965 chipset is fairly contemporary, but if that 2GB/s > DMI connection is the bidirectional bandwidth (likely), then maybe > you're hitting that limit: Intel's DMI bus is based on PCIe, thus will > use 128 byte PCI-e Max Payload packets (as in the rest of the > chipset), which IIRC theoretically maxes you out near 800MB/s. > > The X48 chipset may allow you to crank the Max Payload to 256 (setpci > and the Intel chipset docs), if it doesn't default to 256, like in > 5400 server chipsets. This chipset is where the fun really starts eg > hdparm -T giving >10GB/s, like in Itanium2s ;-) . > > Thanks, > Daniel > -- > Daniel J Blueman > slice 0 does help a little with my 10-disk raid5 for sequential read/writes: http://home.comcast.net/~jpiszcz/raid/20080601/raid5.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/