From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx190.postini.com [74.125.245.190]) by kanga.kvack.org (Postfix) with SMTP id 47DD46B024A for ; Fri, 22 Jun 2012 14:34:29 -0400 (EDT) Received: by obhx4 with SMTP id x4so3012372obh.14 for ; Fri, 22 Jun 2012 11:34:28 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1339176197-13270-1-git-send-email-js1304@gmail.com> <1339176197-13270-4-git-send-email-js1304@gmail.com> Date: Sat, 23 Jun 2012 03:34:27 +0900 Message-ID: Subject: Re: [PATCH 4/4] slub: deactivate freelist of kmem_cache_cpu all at once in deactivate_slab() From: JoonSoo Kim Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Pekka Enberg , linux-kernel@vger.kernel.org, linux-mm@kvack.org 2012/6/10 JoonSoo Kim : > 2012/6/9 Christoph Lameter : >> On Sat, 9 Jun 2012, Joonsoo Kim wrote: >> >>> Current implementation of deactivate_slab() which deactivate >>> freelist of kmem_cache_cpu one by one is inefficient. >>> This patch changes it to deactivate freelist all at once. >>> But, there is no overall performance benefit, >>> because deactivate_slab() is invoked infrequently. >> >> Hmm, deactivate freelist can race with slab_free. Need to look at this in >> detail. > > Implemented logic is nearly same as previous one. > I just merge first step of previous deactivate_slab() with second one. > In case of failure of cmpxchg_double_slab(), reloading page->freelist, > page->counters and recomputing inuse > ensure that race with slab_free() cannot be possible. > In case that we need a lock, try to get a lock before invoking > cmpxchg_double_slab(), > so race with slab_free cannot be occured too. > > Above is my humble opinion, please give me some comments. Hi Pekka and Christoph. Could you give me some comments about this, please? -- 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