From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx115.postini.com [74.125.245.115]) by kanga.kvack.org (Postfix) with SMTP id AC57E6B006C for ; Tue, 20 Nov 2012 10:41:21 -0500 (EST) Received: by mail-ea0-f169.google.com with SMTP id a12so2075996eaa.14 for ; Tue, 20 Nov 2012 07:41:20 -0800 (PST) From: Michal Nazarewicz Subject: Re: [PATCH] mm: cma: allocate pages from CMA if NR_FREE_PAGES approaches low water mark In-Reply-To: <50AB987F.30002@samsung.com> References: <1352710782-25425-1-git-send-email-m.szyprowski@samsung.com> <20121120000137.GC447@bbox> <50AB987F.30002@samsung.com> Date: Tue, 20 Nov 2012 16:41:12 +0100 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="=-=-=" Sender: owner-linux-mm@kvack.org List-ID: To: Marek Szyprowski , Minchan Kim Cc: linux-mm@kvack.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, Kyungmin Park , Andrew Morton , Mel Gorman , Bartlomiej Zolnierkiewicz --=-=-= Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Tue, Nov 20 2012, Marek Szyprowski wrote: > Right now running out of 'plain' movable pages is the only possibility to > get movable pages allocated from CMA. On the other hand running out of > 'plain' movable pages is very deadly for the system, as movable pageblocks > are also the main fallbacks for reclaimable and non-movable pages. > > Then, once we run out of movable pages and kernel needs non-mobable or > reclaimable page (what happens quite often), it usually triggers OOM to > satisfy the memory needs. Such OOM is very strange, especially on a system > with dozen of megabytes of CMA memory, having most of them free at the OOM > event. By high memory pressure I mean the high memory usage. Would it make sense to *always* use MIGRATE_CMA for movable allocations before MIGRATE_MOVABLE? Ie. how about this patch (not tested): ------------------------- >8 ----------------------------------------------= --- --=-=-=--