Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751886Ab1FOLx0 (ORCPT ); Wed, 15 Jun 2011 07:53:26 -0400 Received: from mail-vw0-f46.google.com ([209.85.212.46]:58263 "EHLO mail-vw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750904Ab1FOLxY (ORCPT ); Wed, 15 Jun 2011 07:53:24 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=ffwll.ch; s=google; h=mime-version:x-originating-ip:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; b=dae5CudbqUMJeNh3rNATixkWc34cWYT+Iu/l7QbTsD+JXuqx8wrdTgxPIM5XDSrl+s gPzLqoEyIzRx3uoV11ZR1y3JZB2oTol2MtqQH4qQlF9x8PscZ+FBMekVhSWcpgFbKWWi xascSZmzmBxmjbOiULsUncfje7ShmPt6+nlTA= MIME-Version: 1.0 X-Originating-IP: [212.120.32.74] In-Reply-To: <201106142030.07549.arnd@arndb.de> References: <1307699698-29369-1-git-send-email-m.szyprowski@samsung.com> <201106141803.00876.arnd@arndb.de> <201106142030.07549.arnd@arndb.de> Date: Wed, 15 Jun 2011 13:53:22 +0200 Message-ID: Subject: Re: [Linaro-mm-sig] [PATCH 08/10] mm: cma: Contiguous Memory Allocator added From: Daniel Vetter To: Arnd Bergmann Cc: Michal Nazarewicz , Ankita Garg , Daniel Walker , Jesse Barker , Mel Gorman , linux-kernel@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, Kyungmin Park , KAMEZAWA Hiroyuki , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1357 Lines: 29 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). So if this is only a requirement on very few platforms and can be cheaply fixed with multiple cma allocation areas (heck, we have slabs for the same reasons in the kernel), it might be a sensible compromise. -Daniel -- Daniel Vetter daniel.vetter@ffwll.ch - +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/