From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933488Ab1I1Wt6 (ORCPT ); Wed, 28 Sep 2011 18:49:58 -0400 Received: from cantor2.suse.de ([195.135.220.15]:54982 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933383Ab1I1Wtz (ORCPT ); Wed, 28 Sep 2011 18:49:55 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Wed Sep 28 15:01:49 2011 Message-Id: <20110928220149.611851528@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Wed, 28 Sep 2011 15:03:14 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, KAMEZAWA Hiroyuki , Daisuke Nishimura , Michal Hocko , Ying Han Subject: [230/244] memcg: fix vmscan count in small memcgs In-Reply-To: <20110928220225.GA27128@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.0-stable review patch. If anyone has any objections, please let us know. ------------------ From: KAMEZAWA Hiroyuki commit 4508378b9523e22a2a0175d8bf64d932fb10a67d upstream. Commit 246e87a93934 ("memcg: fix get_scan_count() for small targets") fixes the memcg/kswapd behavior against small targets and prevent vmscan priority too high. But the implementation is too naive and adds another problem to small memcg. It always force scan to 32 pages of file/anon and doesn't handle swappiness and other rotate_info. It makes vmscan to scan anon LRU regardless of swappiness and make reclaim bad. This patch fixes it by adjusting scanning count with regard to swappiness at el. At a test "cat 1G file under 300M limit." (swappiness=20) before patch scanned_pages_by_limit 360919 scanned_anon_pages_by_limit 180469 scanned_file_pages_by_limit 180450 rotated_pages_by_limit 31 rotated_anon_pages_by_limit 25 rotated_file_pages_by_limit 6 freed_pages_by_limit 180458 freed_anon_pages_by_limit 19 freed_file_pages_by_limit 180439 elapsed_ns_by_limit 429758872 after patch scanned_pages_by_limit 180674 scanned_anon_pages_by_limit 24 scanned_file_pages_by_limit 180650 rotated_pages_by_limit 35 rotated_anon_pages_by_limit 24 rotated_file_pages_by_limit 11 freed_pages_by_limit 180634 freed_anon_pages_by_limit 0 freed_file_pages_by_limit 180634 elapsed_ns_by_limit 367119089 scanned_pages_by_system 0 the numbers of scanning anon are decreased(as expected), and elapsed time reduced. By this patch, small memcgs will work better. (*) Because the amount of file-cache is much bigger than anon, recalaim_stat's rotate-scan counter make scanning files more. Signed-off-by: KAMEZAWA Hiroyuki Cc: Daisuke Nishimura Cc: Michal Hocko Cc: Ying Han Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/vmscan.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1748,6 +1748,7 @@ static void get_scan_count(struct zone * enum lru_list l; int noswap = 0; int force_scan = 0; + unsigned long nr_force_scan[2]; anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + @@ -1770,6 +1771,8 @@ static void get_scan_count(struct zone * fraction[0] = 0; fraction[1] = 1; denominator = 1; + nr_force_scan[0] = 0; + nr_force_scan[1] = SWAP_CLUSTER_MAX; goto out; } @@ -1781,6 +1784,8 @@ static void get_scan_count(struct zone * fraction[0] = 1; fraction[1] = 0; denominator = 1; + nr_force_scan[0] = SWAP_CLUSTER_MAX; + nr_force_scan[1] = 0; goto out; } } @@ -1829,6 +1834,11 @@ static void get_scan_count(struct zone * fraction[0] = ap; fraction[1] = fp; denominator = ap + fp + 1; + if (force_scan) { + unsigned long scan = SWAP_CLUSTER_MAX; + nr_force_scan[0] = div64_u64(scan * ap, denominator); + nr_force_scan[1] = div64_u64(scan * fp, denominator); + } out: for_each_evictable_lru(l) { int file = is_file_lru(l); @@ -1849,12 +1859,8 @@ out: * memcg, priority drop can cause big latency. So, it's better * to scan small amount. See may_noscan above. */ - if (!scan && force_scan) { - if (file) - scan = SWAP_CLUSTER_MAX; - else if (!noswap) - scan = SWAP_CLUSTER_MAX; - } + if (!scan && force_scan) + scan = nr_force_scan[file]; nr[l] = scan; } }