From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932497AbbFEMFD (ORCPT ); Fri, 5 Jun 2015 08:05:03 -0400 Received: from mail-pd0-f176.google.com ([209.85.192.176]:33160 "EHLO mail-pd0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932238AbbFEME4 (ORCPT ); Fri, 5 Jun 2015 08:04:56 -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][PATCHv2 3/8] zsmalloc: lower ZS_ALMOST_FULL waterline Date: Fri, 5 Jun 2015 21:03:53 +0900 Message-Id: <1433505838-23058-4-git-send-email-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.4.2.387.gf86f31a In-Reply-To: <1433505838-23058-1-git-send-email-sergey.senozhatsky@gmail.com> References: <1433505838-23058-1-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 lists. ALMOST_EMPTY: [..] inuse: 3 max_objects: 4 inuse: 5 max_objects: 7 inuse: 5 max_objects: 7 inuse: 2 max_objects: 3 [..] 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. In other words, from compaction point of view, 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, but can shorten compaction execution time. 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 cd37bda..b94e281 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -198,7 +198,7 @@ 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 { /* @@ -633,7 +633,7 @@ 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; -- 2.4.2.387.gf86f31a