Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933460AbaJVMC2 (ORCPT ); Wed, 22 Oct 2014 08:02:28 -0400 Received: from mailout32.mail01.mtsvc.net ([216.70.64.70]:56752 "EHLO n23.mail01.mtsvc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933056AbaJVMC0 (ORCPT ); Wed, 22 Oct 2014 08:02:26 -0400 X-Greylist: delayed 60989 seconds by postgrey-1.27 at vger.kernel.org; Wed, 22 Oct 2014 08:02:26 EDT Message-ID: <54479CB2.5040408@hurleysoftware.com> Date: Wed, 22 Oct 2014 08:01:54 -0400 From: Peter Hurley User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Laura Abbott , Hui Zhu , m.szyprowski@samsung.com, akpm@linux-foundation.org, riel@redhat.com, mgorman@suse.de, hughd@google.com, akinobu.mita@gmail.com CC: rjw@rjwysocki.net, len.brown@intel.com, pavel@ucw.cz, mina86@mina86.com, aneesh.kumar@linux.vnet.ibm.com, iamjoonsoo.kim@lge.com, hannes@cmpxchg.org, minchan@kernel.org, nasa4836@gmail.com, ddstreet@ieee.org, mingo@kernel.org, rientjes@google.com, peterz@infradead.org, keescook@chromium.org, atomlin@redhat.com, raistlin@linux.it, axboe@fb.com, paulmck@linux.vnet.ibm.com, kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com, k.khlebnikov@samsung.com, msalter@redhat.com, deller@gmx.de, tangchen@cn.fujitsu.com, ben@decadent.org.uk, vbabka@suse.cz, sasha.levin@oracle.com, vdavydov@parallels.com, suleiman@google.com, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 0/4] (CMA_AGGRESSIVE) Make CMA memory be more aggressive about allocation References: <1413430551-22392-1-git-send-email-zhuhui@xiaomi.com> <543F8812.2020002@codeaurora.org> In-Reply-To: <543F8812.2020002@codeaurora.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Authenticated-User: 990527 peter@hurleysoftware.com X-MT-ID: 8FA290C2A27252AACF65DBC4A42F3CE3735FB2A4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/16/2014 04:55 AM, Laura Abbott wrote: > On 10/15/2014 8:35 PM, Hui Zhu wrote: >> In fallbacks of page_alloc.c, MIGRATE_CMA is the fallback of >> MIGRATE_MOVABLE. >> MIGRATE_MOVABLE will use MIGRATE_CMA when it doesn't have a page in >> order that Linux kernel want. >> >> If a system that has a lot of user space program is running, for >> instance, an Android board, most of memory is in MIGRATE_MOVABLE and >> allocated. Before function __rmqueue_fallback get memory from >> MIGRATE_CMA, the oom_killer will kill a task to release memory when >> kernel want get MIGRATE_UNMOVABLE memory because fallbacks of >> MIGRATE_UNMOVABLE are MIGRATE_RECLAIMABLE and MIGRATE_MOVABLE. >> This status is odd. The MIGRATE_CMA has a lot free memory but Linux >> kernel kill some tasks to release memory. >> >> This patch series adds a new function CMA_AGGRESSIVE to make CMA memory >> be more aggressive about allocation. >> If function CMA_AGGRESSIVE is available, when Linux kernel call function >> __rmqueue try to get pages from MIGRATE_MOVABLE and conditions allow, >> MIGRATE_CMA will be allocated as MIGRATE_MOVABLE first. If MIGRATE_CMA >> doesn't have enough pages for allocation, go back to allocate memory from >> MIGRATE_MOVABLE. >> Then the memory of MIGRATE_MOVABLE can be kept for MIGRATE_UNMOVABLE and >> MIGRATE_RECLAIMABLE which doesn't have fallback MIGRATE_CMA. >> > > It's good to see another proposal to fix CMA utilization. Do you have > any data about the success rate of CMA contiguous allocation after > this patch series? I played around with a similar approach of using > CMA for MIGRATE_MOVABLE allocations and found that although utilization > did increase, contiguous allocations failed at a higher rate and were > much slower. I see what this series is trying to do with avoiding > allocation from CMA pages when a contiguous allocation is progress. > My concern is that there would still be problems with contiguous > allocation after all the MIGRATE_MOVABLE fallback has happened. What impact does this series have on x86 platforms now that CMA is the backup allocator for all iommu dma allocations? Regards, Peter Hurley -- 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/