From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: libata: set queue SSD flag for SSD devices Date: Sat, 11 Oct 2008 09:33:37 +0200 Message-ID: <1223710417.4159.11.camel@localhost.localdomain> References: <200810101904.m9AJ42Gq018897@hera.kernel.org> <20081010202515.446857cc@lxorguk.ukuu.org.uk> <20081010200528.GJ19428@kernel.dk> <20081010175508.3d1ed2a4@infradead.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from accolon.hansenpartnership.com ([76.243.235.52]:55552 "EHLO accolon.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750816AbYJKHdp (ORCPT ); Sat, 11 Oct 2008 03:33:45 -0400 In-Reply-To: <20081010175508.3d1ed2a4@infradead.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Arjan van de Ven Cc: Jens Axboe , Alan Cox , Linux Kernel Mailing List , linux-ide@vger.kernel.org, torvalds@osdl.org On Fri, 2008-10-10 at 17:55 -0700, Arjan van de Ven wrote: > On Fri, 10 Oct 2008 22:05:28 +0200 > Jens Axboe wrote: > > > > In this specific patch, it'll do no harm at least since I very much > > doubt we'll see a false positive. And even if, the consequences wont > > be dire. But it does want the version check, of course. > > > > also, is "is an ssd" the right question or is "doesn't have seek > latency" the right one? > (difference is.. well EMC boxes with lots of ram etc) For libata, the is ssd is the right test. For things like the symmetrix we probably need to look at the caching mode page and treat it like ssd if the cache is say > 1GB or whatever heuristic is needed. James