From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f69.google.com (mail-pa0-f69.google.com [209.85.220.69]) by kanga.kvack.org (Postfix) with ESMTP id 61A286B0038 for ; Tue, 18 Oct 2016 09:25:17 -0400 (EDT) Received: by mail-pa0-f69.google.com with SMTP id fn2so231631166pad.7 for ; Tue, 18 Oct 2016 06:25:17 -0700 (PDT) Received: from mga05.intel.com (mga05.intel.com. [192.55.52.43]) by mx.google.com with ESMTPS id w20si32290871pgj.4.2016.10.18.06.25.15 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 18 Oct 2016 06:25:16 -0700 (PDT) Subject: Re: [Intel-gfx] [PATCH v4 2/2] drm/i915: Make GPU pages movable References: <1459775891-32442-1-git-send-email-chris@chris-wilson.co.uk> <1459775891-32442-2-git-send-email-chris@chris-wilson.co.uk> <1476792301.3117.14.camel@linux.intel.com> From: "Goel, Akash" Message-ID: Date: Tue, 18 Oct 2016 18:55:12 +0530 MIME-Version: 1.0 In-Reply-To: <1476792301.3117.14.camel@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Joonas Lahtinen , Chris Wilson Cc: intel-gfx@lists.freedesktop.org, akash.goel@intel.com, linux-mm@kvack.org, Hugh Dickins , Sourab Gupta On 10/18/2016 5:35 PM, Joonas Lahtinen wrote: > On ma, 2016-04-04 at 14:18 +0100, Chris Wilson wrote: >> From: Akash Goel >> >> On a long run of more than 2-3 days, physical memory tends to get >> fragmented severely, which considerably slows down the system. In such a >> scenario, the shrinker is also unable to help as lack of memory is not >> the actual problem, since it has been observed that there are enough free >> pages of 0 order. This also manifests itself when an indiviual zone in >> the mm runs out of pages and if we cannot migrate pages between zones, >> the kernel hits an out-of-memory even though there are free pages (and >> often all of swap) available. >> >> To address the issue of external fragementation, kernel does a compaction >> (which involves migration of pages) but it's efficacy depends upon how >> many pages are marked as MOVABLE, as only those pages can be migrated. >> >> Currently the backing pages for GFX buffers are allocated from shmemfs >> with GFP_RECLAIMABLE flag, in units of 4KB pages. In the case of limited >> swap space, it may not be possible always to reclaim or swap-out pages of >> all the inactive objects, to make way for free space allowing formation >> of higher order groups of physically-contiguous pages on compaction. >> >> Just marking the GPU pages as MOVABLE will not suffice, as i915.ko has to >> pin the pages if they are in use by GPU, which will prevent their >> migration. So the migratepage callback in shmem is also hooked up to get >> a notification when kernel initiates the page migration. On the >> notification, i915.ko appropriately unpin the pages. With this we can >> effectively mark the GPU pages as MOVABLE and hence mitigate the >> fragmentation problem. >> >> v2: >> - Rename the migration routine to gem_shrink_migratepage, move it to the >> shrinker file, and use the existing constructs (Chris) >> - To cleanup, add a new helper function to encapsulate all page migration >> skip conditions (Chris) >> - Add a new local helper function in shrinker file, for dropping the >> backing pages, and call the same from gem_shrink() also (Chris) >> >> v3: >> - Fix/invert the check on the return value of unsafe_drop_pages (Chris) >> >> v4: >> - Minor tidy >> >> Testcase: igt/gem_shrink >> Bugzilla: (e.g.) https://bugs.freedesktop.org/show_bug.cgi?id=90254 >> Cc: Hugh Dickins >> Cc: linux-mm@kvack.org >> Signed-off-by: Sourab Gupta >> Signed-off-by: Akash Goel >> Reviewed-by: Chris Wilson > > Could this patch be re-spinned on top of current nightly? > Sure will rebase it on top of nightly. > After removing; > >> WARN(page_count(newpage) != 1, "Unexpected ref count for newpage\n") > > and > >> if (ret) >> DRM_DEBUG_DRIVER("page=%p migration returned %d\n", page, ret); > > This is; > > Reviewed-by: Joonas Lahtinen Thanks much for the review. But there is a precursor patch also, there has been no traction on that. [1/2] shmem: Support for registration of Driver/file owner specific ops https://patchwork.freedesktop.org/patch/77935/ Best regards Akash > > Regards, Joonas > -- 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