From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f179.google.com (mail-ig0-f179.google.com [209.85.213.179]) by kanga.kvack.org (Postfix) with ESMTP id E66BC6B0032 for ; Wed, 10 Dec 2014 12:37:59 -0500 (EST) Received: by mail-ig0-f179.google.com with SMTP id r2so3326697igi.0 for ; Wed, 10 Dec 2014 09:37:59 -0800 (PST) Received: from resqmta-po-05v.sys.comcast.net ([2001:558:fe16:19:250:56ff:feb0:2995]) by mx.google.com with ESMTPS id cj5si3660583igc.29.2014.12.10.09.37.58 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Wed, 10 Dec 2014 09:37:58 -0800 (PST) Date: Wed, 10 Dec 2014 11:37:56 -0600 (CST) From: Christoph Lameter 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: owner-linux-mm@kvack.org List-ID: To: Pekka Enberg Cc: akpm , Steven Rostedt , LKML , Thomas Gleixner , "linux-mm@kvack.org" , iamjoonsoo@lge.com, Jesper Dangaard Brouer 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, 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