From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934112Ab3FSIwj (ORCPT ); Wed, 19 Jun 2013 04:52:39 -0400 Received: from LGEMRELSE7Q.lge.com ([156.147.1.151]:64569 "EHLO LGEMRELSE7Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933755Ab3FSIwd (ORCPT ); Wed, 19 Jun 2013 04:52:33 -0400 X-AuditID: 9c930197-b7beaae000004876-c2-51c1714f21b0 Date: Wed, 19 Jun 2013 17:52:50 +0900 From: Joonsoo Kim To: Wanpeng Li Cc: Pekka Enberg , Christoph Lameter , Matt Mackall , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] slub: do not put a slab to cpu partial list when cpu_partial is 0 Message-ID: <20130619085250.GC12231@lge.com> References: <1371623635-26575-1-git-send-email-iamjoonsoo.kim@lge.com> <51c1652d.246e320a.4057.ffffed4fSMTPIN_ADDED_BROKEN@mx.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51c1652d.246e320a.4057.ffffed4fSMTPIN_ADDED_BROKEN@mx.google.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 19, 2013 at 04:00:32PM +0800, Wanpeng Li wrote: > On Wed, Jun 19, 2013 at 03:33:55PM +0900, Joonsoo Kim wrote: > >In free path, we don't check number of cpu_partial, so one slab can > >be linked in cpu partial list even if cpu_partial is 0. To prevent this, > >we should check number of cpu_partial in put_cpu_partial(). > > > > How about skip get_partial entirely? put_cpu_partial is called > in two paths, one is during refill cpu partial lists in alloc > slow path, the other is in free slow path. And cpu_partial is 0 > just in debug mode. > > - alloc slow path, there is unnecessary to call get_partial > since cpu partial lists won't be used in debug mode. > - free slow patch, new.inuse won't be true in debug mode > which lead to put_cpu_partial won't be called. > In debug mode, put_cpu_partial() can't be called already on both path. But, if we assign 0 to cpu_partial via sysfs, put_cpu_partial() will be called on free slow path. On alloc slow path, it can't be called, because following test in get_partial_node() is always failed. available > s->cpu_partial / 2 Thanks. > Regards, > Wanpeng Li > > >Signed-off-by: Joonsoo Kim > > > >diff --git a/mm/slub.c b/mm/slub.c > >index 57707f0..7033b4f 100644 > >--- a/mm/slub.c > >+++ b/mm/slub.c > >@@ -1955,6 +1955,9 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) > > int pages; > > int pobjects; > > > >+ if (!s->cpu_partial) > >+ return; > >+ > > do { > > pages = 0; > > pobjects = 0; > >-- > >1.7.9.5 > > > >-- > >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 > > -- > 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