From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756503AbbE2PJC (ORCPT ); Fri, 29 May 2015 11:09:02 -0400 Received: from mail-pa0-f45.google.com ([209.85.220.45]:34446 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756649AbbE2PGt (ORCPT ); Fri, 29 May 2015 11:06:49 -0400 From: Sergey Senozhatsky To: Andrew Morton , Minchan Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , Sergey Senozhatsky Subject: [RFC][PATCH 10/10] zsmalloc: lower ZS_ALMOST_FULL waterline Date: Sat, 30 May 2015 00:05:28 +0900 Message-Id: <1432911928-14654-11-git-send-email-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.4.2.337.gfae46aa In-Reply-To: <1432911928-14654-1-git-send-email-sergey.senozhatsky@gmail.com> References: <1432911928-14654-1-git-send-email-sergey.senozhatsky@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org get_fullness_group() considers 3/4 full pages as almost empty. that, unfortunately, marks as ALMOST_EMPTY pages that we would probably like to keep in ALMOST_FULL list. ALMOST_EMPTY: [..] inuse: 3 max_objexts: 4 inuse: 5 max_objexts: 7 inuse: 5 max_objexts: 7 inuse: 2 max_objexts: 3 [..] so, for "inuse: 5 max_objexts: 7" ALMOST_EMPTY page, for example, it'll take 2 obj_malloc to make the page FULL and 5 obj_free to make it EMPTY. compaction selects ALMOST_EMPTY pages as source pages, which can result in extra object moves. iow, in terms of compaction, it makes more sense to fill this page, rather than drain it. decrease ALMOST_FULL waterline to 2/3 of max capacity; which is, of course, still imperfect. Signed-off-by: Sergey Senozhatsky --- mm/zsmalloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 0524c4a..a8a3eae 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -196,7 +196,7 @@ static int zs_size_classes; * * (see: fix_fullness_group()) */ -static const int fullness_threshold_frac = 4; +static const int fullness_threshold_frac = 3; struct size_class { spinlock_t lock; @@ -612,7 +612,7 @@ static enum fullness_group get_fullness_group(struct page *page) fg = ZS_EMPTY; else if (inuse == max_objects) fg = ZS_FULL; - else if (inuse <= 3 * max_objects / fullness_threshold_frac) + else if (inuse <= 2 * max_objects / fullness_threshold_frac) fg = ZS_ALMOST_EMPTY; else fg = ZS_ALMOST_FULL; -- 2.4.2.337.gfae46aa