Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932430AbaLJRiC (ORCPT ); Wed, 10 Dec 2014 12:38:02 -0500 Received: from resqmta-po-05v.sys.comcast.net ([96.114.154.164]:48618 "EHLO resqmta-po-05v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757620AbaLJRh6 (ORCPT ); Wed, 10 Dec 2014 12:37:58 -0500 Date: Wed, 10 Dec 2014 11:37:56 -0600 (CST) From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Pekka Enberg cc: akpm , Steven Rostedt , LKML , Thomas Gleixner , "linux-mm@kvack.org" , iamjoonsoo@lge.com, Jesper Dangaard Brouer Subject: Re: [PATCH 3/7] slub: Do not use c->page on free In-Reply-To: Message-ID: References: <20141210163017.092096069@linux.com> <20141210163033.717707217@linux.com> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 10 Dec 2014, Pekka Enberg wrote: > I'm fine with the optimization: > > Reviewed-by: Pekka Enberg There were some other issues so its now: Subject: slub: Do not use c->page on free Avoid using the page struct address on free by just doing an address comparison. That is easily doable now that the page address is available in the page struct and we already have the page struct address of the object to be freed calculated. Reviewed-by: Pekka Enberg Signed-off-by: Christoph Lameter Index: linux/mm/slub.c =================================================================== --- linux.orig/mm/slub.c 2014-12-10 11:35:32.538563734 -0600 +++ linux/mm/slub.c 2014-12-10 11:36:39.032447807 -0600 @@ -2625,6 +2625,17 @@ slab_empty: discard_slab(s, page); } +static bool is_pointer_to_page(struct page *page, void *p) +{ + long d = p - page->address; + + /* + * Do a comparison for a MAX_ORDER page first before using + * compound_order() to determine the actual page size. + */ + return d >= 0 && d < (1 << MAX_ORDER) && d < (compound_order(page) << PAGE_SHIFT); +} + /* * Fastpath with forced inlining to produce a kfree and kmem_cache_free that * can perform fastpath freeing without additional function calls. @@ -2658,7 +2669,7 @@ redo: tid = c->tid; preempt_enable(); - if (likely(page == c->page)) { + if (likely(is_pointer_to_page(page, c->freelist))) { set_freepointer(s, object, c->freelist); if (unlikely(!this_cpu_cmpxchg_double( -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/