From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id C42A26B0012 for ; Wed, 15 Jun 2011 09:13:24 -0400 (EDT) Message-ID: <4DF8AFB5.10205@vmware.com> Date: Wed, 15 Jun 2011 15:12:21 +0200 From: Thomas Hellstrom MIME-Version: 1.0 Subject: Re: [Linaro-mm-sig] [PATCH 08/10] mm: cma: Contiguous Memory Allocator added References: <1307699698-29369-1-git-send-email-m.szyprowski@samsung.com> <201106141803.00876.arnd@arndb.de> <201106142030.07549.arnd@arndb.de> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Daniel Vetter Cc: Arnd Bergmann , linux-arm-kernel@lists.infradead.org, Daniel Walker , linux-mm@kvack.org, Mel Gorman , linux-kernel@vger.kernel.org, Michal Nazarewicz , linaro-mm-sig@lists.linaro.org, Jesse Barker , Kyungmin Park , Ankita Garg , Andrew Morton , KAMEZAWA Hiroyuki , linux-media@vger.kernel.org On 06/15/2011 01:53 PM, Daniel Vetter wrote: > On Tue, Jun 14, 2011 at 20:30, Arnd Bergmann wrote: > >> On Tuesday 14 June 2011 18:58:35 Michal Nazarewicz wrote: >> >>> Ah yes, I forgot that separate regions for different purposes could >>> decrease fragmentation. >>> >> That is indeed a good point, but having a good allocator algorithm >> could also solve this. I don't know too much about these allocation >> algorithms, but there are probably multiple working approaches to this. >> > imo no allocator algorithm is gonna help if you have comparably large, > variable-sized contiguous allocations out of a restricted address range. > It might work well enough if there are only a few sizes and/or there's > decent headroom. But for really generic workloads this would require > sync objects and eviction callbacks (i.e. what Thomas Hellstrom pushed > with ttm). > Indeed, IIRC on the meeting I pointed out that there is no way to generically solve the fragmentation problem without movable buffers. (I'd do it as a simple CMA backend to TTM). This is exactly the same problem as trying to fit buffers in a limited VRAM area. /Thomas -- 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