From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758223Ab2EBB6A (ORCPT ); Tue, 1 May 2012 21:58:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:19754 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757445Ab2EBB56 (ORCPT ); Tue, 1 May 2012 21:57:58 -0400 Date: Wed, 2 May 2012 03:57:41 +0200 From: Andrea Arcangeli To: Johannes Weiner Cc: linux-mm@kvack.org, Rik van Riel , Peter Zijlstra , Mel Gorman , Andrew Morton , Minchan Kim , Hugh Dickins , KOSAKI Motohiro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [patch 5/5] mm: refault distance-based file cache sizing Message-ID: <20120502015741.GE22923@redhat.com> References: <1335861713-4573-1-git-send-email-hannes@cmpxchg.org> <1335861713-4573-6-git-send-email-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1335861713-4573-6-git-send-email-hannes@cmpxchg.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 01, 2012 at 10:41:53AM +0200, Johannes Weiner wrote: > frequently used active page. Instead, for each refault with a > distance smaller than the size of the active list, we deactivate an Shouldn't this be the size of active list + size of inactive list? If the active list is 500M, inactive 500M and the new working set is 600M, the refault distance will be 600M, it won't be smaller than the size of the active list, and it won't deactivate the active list as it should and it won't be detected as working set. Only the refault distance bigger than inactive+active should not deactivate the active list if I understand how this works correctly. > @@ -1726,6 +1728,11 @@ zonelist_scan: > if ((alloc_flags & ALLOC_CPUSET) && > !cpuset_zone_allowed_softwall(zone, gfp_mask)) > continue; > + if ((alloc_flags & ALLOC_WMARK_LOW) && > + current->refault_distance && > + !workingset_zone_alloc(zone, current->refault_distance, > + &distance, &active)) > + continue; > /* > * When allocating a page cache page for writing, we > * want to get it from a zone that is within its dirty It's a bit hard to see how this may not run oom prematurely if the distance is always bigger, this is just an implementation question and maybe I'm missing a fallback somewhere where we actually allocate memory from whatever place in case no place is ideal. > + /* > + * Lower zones may not even be full, and free pages are > + * potential inactive space, too. But the dirty reserve is > + * not available to page cache due to lowmem reserves and the > + * kswapd watermark. Don't include it. > + */ > + zone_free = zone_page_state(zone, NR_FREE_PAGES); > + if (zone_free > zone->dirty_balance_reserve) > + zone_free -= zone->dirty_balance_reserve; > + else > + zone_free = 0; Maybe also remove the high wmark from the sum? It can be some hundred meg so it's better to take it into account, to have a more accurate math and locate the best zone that surely fits. For the same reason it looks like the lowmem reserve should also be taken into account, on the full sum. > + if (missing >= zone_active + zone_free) { This seems a place where to add the zone_inactive too according to my comment on top. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Arcangeli Subject: Re: [patch 5/5] mm: refault distance-based file cache sizing Date: Wed, 2 May 2012 03:57:41 +0200 Message-ID: <20120502015741.GE22923@redhat.com> References: <1335861713-4573-1-git-send-email-hannes@cmpxchg.org> <1335861713-4573-6-git-send-email-hannes@cmpxchg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-mm@kvack.org, Rik van Riel , Peter Zijlstra , Mel Gorman , Andrew Morton , Minchan Kim , Hugh Dickins , KOSAKI Motohiro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Johannes Weiner Return-path: Content-Disposition: inline In-Reply-To: <1335861713-4573-6-git-send-email-hannes@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Tue, May 01, 2012 at 10:41:53AM +0200, Johannes Weiner wrote: > frequently used active page. Instead, for each refault with a > distance smaller than the size of the active list, we deactivate an Shouldn't this be the size of active list + size of inactive list? If the active list is 500M, inactive 500M and the new working set is 600M, the refault distance will be 600M, it won't be smaller than the size of the active list, and it won't deactivate the active list as it should and it won't be detected as working set. Only the refault distance bigger than inactive+active should not deactivate the active list if I understand how this works correctly. > @@ -1726,6 +1728,11 @@ zonelist_scan: > if ((alloc_flags & ALLOC_CPUSET) && > !cpuset_zone_allowed_softwall(zone, gfp_mask)) > continue; > + if ((alloc_flags & ALLOC_WMARK_LOW) && > + current->refault_distance && > + !workingset_zone_alloc(zone, current->refault_distance, > + &distance, &active)) > + continue; > /* > * When allocating a page cache page for writing, we > * want to get it from a zone that is within its dirty It's a bit hard to see how this may not run oom prematurely if the distance is always bigger, this is just an implementation question and maybe I'm missing a fallback somewhere where we actually allocate memory from whatever place in case no place is ideal. > + /* > + * Lower zones may not even be full, and free pages are > + * potential inactive space, too. But the dirty reserve is > + * not available to page cache due to lowmem reserves and the > + * kswapd watermark. Don't include it. > + */ > + zone_free = zone_page_state(zone, NR_FREE_PAGES); > + if (zone_free > zone->dirty_balance_reserve) > + zone_free -= zone->dirty_balance_reserve; > + else > + zone_free = 0; Maybe also remove the high wmark from the sum? It can be some hundred meg so it's better to take it into account, to have a more accurate math and locate the best zone that surely fits. For the same reason it looks like the lowmem reserve should also be taken into account, on the full sum. > + if (missing >= zone_active + zone_free) { This seems a place where to add the zone_inactive too according to my comment on top. -- 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/ . 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