From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f171.google.com (mail-qc0-f171.google.com [209.85.216.171]) by kanga.kvack.org (Postfix) with ESMTP id 22C226B0071 for ; Wed, 22 Oct 2014 08:02:28 -0400 (EDT) Received: by mail-qc0-f171.google.com with SMTP id i17so2614311qcy.30 for ; Wed, 22 Oct 2014 05:02:27 -0700 (PDT) Received: from n23.mail01.mtsvc.net (mailout32.mail01.mtsvc.net. [216.70.64.70]) by mx.google.com with ESMTPS id n69si27503228qga.24.2014.10.22.05.02.25 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Oct 2014 05:02:25 -0700 (PDT) Message-ID: <54479CB2.5040408@hurleysoftware.com> Date: Wed, 22 Oct 2014 08:01:54 -0400 From: Peter Hurley MIME-Version: 1.0 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 Sender: owner-linux-mm@kvack.org List-ID: 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 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, 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/ . Don't email: email@kvack.org