Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751556AbaKFM3v (ORCPT ); Thu, 6 Nov 2014 07:29:51 -0500 Received: from mail-wi0-f181.google.com ([209.85.212.181]:47269 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751431AbaKFM3r convert rfc822-to-8bit (ORCPT ); Thu, 6 Nov 2014 07:29:47 -0500 From: Michal Nazarewicz To: Weijie Yang Cc: Gregory Fong , linux-mm@kvack.org, Laura Abbott , iamjoonsoo.kim@lge.com, Marek Szyprowski , "linux-kernel\@vger.kernel.org" , Florian Fainelli , Brian Norris Subject: Re: CMA alignment question In-Reply-To: Organization: http://mina86.com/ References: User-Agent: Notmuch/0.17+15~gb65ca8e (http://notmuchmail.org) Emacs/25.0.50.1 (x86_64-unknown-linux-gnu) X-Face: PbkBB1w#)bOqd`iCe"Ds{e+!C7`pkC9a|f)Qo^BMQvy\q5x3?vDQJeN(DS?|-^$uMti[3D*#^_Ts"pU$jBQLq~Ud6iNwAw_r_o_4]|JO?]}P_}Nc&"p#D(ZgUb4uCNPe7~a[DbPG0T~!&c.y$Ur,=N4RT>]dNpd;KFrfMCylc}gc??'U2j,!8%xdD Face: 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 X-PGP: 50751FF4 X-PGP-FP: AC1F 5F5C D418 88F8 CC84 5858 2060 4012 5075 1FF4 X-Hashcash: 1:20:141106:computersforpeace@gmail.com::imo6baGjTetVhdxZ:000000000000000000000000000000000010oc X-Hashcash: 1:20:141106:weijie.yang.kh@gmail.com::ja/8IucDv93hemnm:00000000000000000000000000000000000001WMW X-Hashcash: 1:20:141106:gregory.0xf0@gmail.com::piOFRXeXe8IwZKCQ:0000000000000000000000000000000000000001ehv X-Hashcash: 1:20:141106:linux-mm@kvack.org::gMYJlw7bECsDFxJT:00000000000000000000000000000000000000000003fXQ X-Hashcash: 1:20:141106:f.fainelli@gmail.com::3BIaEFSJYKShqU3v:000000000000000000000000000000000000000005/cW X-Hashcash: 1:20:141106:iamjoonsoo.kim@lge.com::AxBy/rgy3O8CNTMp:0000000000000000000000000000000000000005r+t X-Hashcash: 1:20:141106:m.szyprowski@samsung.com::/+5ruf+y4N7/vs0c:0000000000000000000000000000000000000B51G X-Hashcash: 1:20:141106:linux-kernel@vger.kernel.org::7oaSyoHz457/6G8P:000000000000000000000000000000000An5c X-Hashcash: 1:20:141106:lauraa@codeaurora.org::TUlm//kdQO62MPka:0000000000000000000000000000000000000000HmI1 Date: Thu, 06 Nov 2014 13:29:42 +0100 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 06 2014, Weijie Yang wrote: > I agree the current code doesn't handle this issue properly. > However, I prefer to add specific usage to CMA interface rather than > modify the cma code, Because the latter hide the issue and could waste > memory. cma_alloc should handle whatever alignment caller uses. Sure, if CMA area has smaller alignment this may lead to wasted memory, but so can allocation with small alignment followed by allocation with big alignment. If you're saying that platform should try to get the CMA area aligned such that no alignment offset happens I agree. If you're saying that cma_alloc should fail (to properly align) an allocation request, I disagree. -- Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michał “mina86” Nazarewicz (o o) ooo +------ooO--(_)--Ooo-- -- 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/