From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH 1/8] block: limit default readahead size for small devices Date: Mon, 21 Nov 2011 13:47:15 +0100 Message-ID: <20111121124715.GD24062@one.firstfloor.org> References: <20111121091819.394895091@intel.com> <20111121093846.121502745@intel.com> <20111121100004.GB5084@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Wu Fengguang , Andrew Morton , Linux Memory Management List , linux-fsdevel@vger.kernel.org, Li Shaohua , Clemens Ladisch , Jens Axboe , Rik van Riel , LKML , Andi Kleen To: Christoph Hellwig Return-path: Content-Disposition: inline In-Reply-To: <20111121100004.GB5084@infradead.org> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Mon, Nov 21, 2011 at 05:00:04AM -0500, Christoph Hellwig wrote: > On Mon, Nov 21, 2011 at 05:18:20PM +0800, Wu Fengguang wrote: > > Given that the non-rotational attribute is not always reported, we can > > take disk size as a max readahead size hint. This patch uses a formula > > that generates the following concrete limits: > > Given that you mentioned the rotational flag and device size in this > mail, as well as benchmarking with an intel SSD - did you measure > how useful large read ahead sizes still are with highend Flash device > that have extremly high read IOP rates? The more the IOPs the larger the "window" you need to keep everything going I suspect. -Andi -- ak@linux.intel.com -- Speaking for myself only. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org