From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f47.google.com (mail-wm0-f47.google.com [74.125.82.47]) by kanga.kvack.org (Postfix) with ESMTP id B174C6B0038 for ; Fri, 20 Nov 2015 13:37:22 -0500 (EST) Received: by wmdw130 with SMTP id w130so30334231wmd.0 for ; Fri, 20 Nov 2015 10:37:22 -0800 (PST) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id z76si1090462wmz.87.2015.11.20.10.37.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 20 Nov 2015 10:37:21 -0800 (PST) Date: Fri, 20 Nov 2015 13:37:07 -0500 From: Johannes Weiner Subject: Re: [PATCH] vmscan: do not force-scan file lru if its absolute size is small Message-ID: <20151120183707.GA5623@cmpxchg.org> References: <1448038976-28796-1-git-send-email-vdavydov@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1448038976-28796-1-git-send-email-vdavydov@virtuozzo.com> Sender: owner-linux-mm@kvack.org List-ID: To: Vladimir Davydov Cc: Andrew Morton , Michal Hocko , Vlastimil Babka , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Fri, Nov 20, 2015 at 08:02:56PM +0300, Vladimir Davydov wrote: > We assume there is enough inactive page cache if the size of inactive > file lru is greater than the size of active file lru, in which case we > force-scan file lru ignoring anonymous pages. While this logic works > fine when there are plenty of page cache pages, it fails if the size of > file lru is small (several MB): in this case (lru_size >> prio) will be > 0 for normal scan priorities, as a result, if inactive file lru happens > to be larger than active file lru, anonymous pages of a cgroup will > never get evicted unless the system experiences severe memory pressure, > even if there are gigabytes of unused anonymous memory there, which is > unfair in respect to other cgroups, whose workloads might be page cache > oriented. > > This patch attempts to fix this by elaborating the "enough inactive page > cache" check: it makes it not only check that inactive lru size > active > lru size, but also that we will scan something from the cgroup at the > current scan priority. If these conditions do not hold, we proceed to > SCAN_FRACT as usual. > > Signed-off-by: Vladimir Davydov This makes sense, the inactive:active ratio of the file list alone does not give the full picture to decide whether to skip anonymous. Acked-by: Johannes Weiner > @@ -2046,7 +2046,8 @@ static void get_scan_count(struct lruvec *lruvec, int swappiness, > * There is enough inactive page cache, do not reclaim > * anything from the anonymous working set right now. > */ > - if (!inactive_file_is_low(lruvec)) { > + if (!inactive_file_is_low(lruvec) && > + get_lru_size(lruvec, LRU_INACTIVE_FILE) >> sc->priority > 0) { The > 0 seems unnecessary, no? There are too many > in this line :-) -- 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