Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755082AbZDXPSg (ORCPT ); Fri, 24 Apr 2009 11:18:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752215AbZDXPSX (ORCPT ); Fri, 24 Apr 2009 11:18:23 -0400 Received: from rcsinet13.oracle.com ([148.87.113.125]:55502 "EHLO rgminet13.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751110AbZDXPSW (ORCPT ); Fri, 24 Apr 2009 11:18:22 -0400 To: Carl Henrik Lunde Cc: "Martin K. Petersen" , Jeff Garzik , Kay Sievers , rwheeler@redhat.com, snitzer@redhat.com, neilb@suse.de, James.Bottomley@hansenpartnership.com, dgilbert@interlog.com, jens.axboe@oracle.com, matthew@wil.cx, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, LKML Subject: Re: [PATCH 2 of 9] block: Export I/O topology for block devices and partitions From: "Martin K. Petersen" Organization: Oracle References: <72f4e15760670febdb40.1240551143@sermon.lab.mkp.net> <49F1B68D.3010304@garzik.org> Date: Fri, 24 Apr 2009 11:16:32 -0400 In-Reply-To: (Carl Henrik Lunde's message of "Fri, 24 Apr 2009 16:37:17 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.91 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Source-IP: acsmt701.oracle.com [141.146.40.71] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A010202.49F1D7D9.02C7:SCFMA4539814,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1402 Lines: 30 >>>>> "Carl" == Carl Henrik Lunde writes: Carl> Would it also be possible and useful to include the number of Carl> spindles/channels, i.e., how many requests the device can handle Carl> concurrently? CFQ could for example serve two time slices Carl> concurrently if you have sequential reads and the device reports Carl> two spindles. We don't really have a way to get that information at this point. The values exported in my patch set is what the storage vendors in T10 could agree on. I simply applied them to DM and MD devices as well. We're talking to SSD vendors about having their devices export some characteristics that would allow us to schedule I/O more intelligently. The effort of defining what those values might be is work in progress. There has been murmurs about T13 adopting the T10 knobs, much like it happened with form factor and media rotation rate. For more traditional storage we don't really have a good way to distinguish between a 10GB LUN on a million dollar array and a single disk drive. Rotation rate can help and we already use and export that. -- Martin K. Petersen Oracle Linux Engineering -- 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/