From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [RFC PATCH v2] Add new elevator ops for request hint Date: Thu, 11 Aug 2011 15:41:15 +0200 Message-ID: <4E43DBFB.6020105@fusionio.com> References: <20110811004216.GA24810@july> <20110811133302.GC8552@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from mx2.fusionio.com ([66.114.96.31]:33327 "EHLO mx2.fusionio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751033Ab1HKNlZ (ORCPT ); Thu, 11 Aug 2011 09:41:25 -0400 In-Reply-To: <20110811133302.GC8552@redhat.com> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Vivek Goyal Cc: Kyungmin Park , "linux-kernel@vger.kernel.org" , "arnd@arndb.de" , "jh80.chung@samsung.com" , "shli@kernel.org" , "linux-mmc@vger.kernel.org" On 2011-08-11 15:33, Vivek Goyal wrote: > On Thu, Aug 11, 2011 at 09:42:16AM +0900, Kyungmin Park wrote: >> Hi Jens >> >> Now eMMC device requires the upper layer information to improve the data >> performance and reliability. >> >> . Context ID >> Using the context information, it can sort out the data internally and improve the performance. >> The main problem is that it's needed to define "What's the context". >> Actually I expect cfq queue has own unique ID but it doesn't so decide to use the pid instead >> > > Hi, > > Can you please give little more details about the optimization you will > do with this pid information? It is provided in one of the other email threads for this patch. > Also what happens in the case of noop and deadline which don't maintain > per process queues and can't provide this information. It'll still work, it isn't really tied to the CFQ way of diviying things up. >> First I expect the REQ_META but current ext4 doesn't pass the WRITE_META. only use the READ_META. so it needs to investigate it. > > So are you planning to later fix file systems to appropriately mark meta > data requests? One thing that occured to me is that equating META to HOT is not necessarily a good idea. Meta data isn't necessarily more "hot" than regular data, it all depends on how it's being used. So I think it would be a lot more appropriate to pass down this information specifically, instead of overloading REQ_META. -- Jens Axboe