From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id 3BCA76B004D for ; Sat, 10 Oct 2009 13:41:59 -0400 (EDT) Date: Sat, 10 Oct 2009 10:41:11 -0700 From: Andrew Morton Subject: Re: [PATCH] mm: make VM_MAX_READAHEAD configurable Message-Id: <20091010104111.547d8abe.akpm@linux-foundation.org> In-Reply-To: <20091010124042.GA9179@localhost> References: <1255087175-21200-1-git-send-email-ehrhardt@linux.vnet.ibm.com> <1255090830.8802.60.camel@laptop> <20091009122952.GI9228@kernel.dk> <20091009143124.1241a6bc.akpm@linux-foundation.org> <20091010105333.GR9228@kernel.dk> <20091010124042.GA9179@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: Jens Axboe , Peter Zijlstra , Ehrhardt Christian , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Martin Schwidefsky List-ID: On Sat, 10 Oct 2009 20:40:42 +0800 Wu Fengguang wrote: > > not sure if it attempts to do anything based on how quickly > > the device is doing IO. Wu? > > Not for current kernel. But in fact it's possible to estimate the > read speed for each individual sequential stream, and possibly drop > some hint to the IO scheduler: someone will block on this IO after 3 > seconds. But it may not deserve the complexity. Well, we have a test case. Would any of your design proposals address the performance problem which motivated the s390 guys to propose this patch? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org