From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx203.postini.com [74.125.245.203]) by kanga.kvack.org (Postfix) with SMTP id 8B9226B005C for ; Tue, 29 May 2012 10:42:08 -0400 (EDT) Date: Tue, 29 May 2012 09:42:03 -0500 (CDT) From: Christoph Lameter Subject: Re: [PATCH v3 15/28] slub: always get the cache from its page in kfree In-Reply-To: <1337951028-3427-16-git-send-email-glommer@parallels.com> Message-ID: References: <1337951028-3427-1-git-send-email-glommer@parallels.com> <1337951028-3427-16-git-send-email-glommer@parallels.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Glauber Costa Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, kamezawa.hiroyu@jp.fujitsu.com, Tejun Heo , Li Zefan , Greg Thelen , Suleiman Souhlal , Michal Hocko , Johannes Weiner , devel@openvz.org, David Rientjes , Pekka Enberg On Fri, 25 May 2012, Glauber Costa wrote: > struct page already have this information. If we start chaining > caches, this information will always be more trustworthy than > whatever is passed into the function Yes but the lookup of the page struct also costs some cycles. SLAB in !NUMA mode and SLOB avoid these lookups and can improve their freeing speed because of that. > diff --git a/mm/slub.c b/mm/slub.c > index 0eb9e72..640872f 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2598,10 +2598,14 @@ redo: > void kmem_cache_free(struct kmem_cache *s, void *x) > { > struct page *page; > + bool slab_match; > > page = virt_to_head_page(x); > > - slab_free(s, page, x, _RET_IP_); > + slab_match = (page->slab == s) | slab_is_parent(page->slab, s); > + VM_BUG_ON(!slab_match); Why add a slab_match bool if you do not really need it? -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org