Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751492AbaLPHyO (ORCPT ); Tue, 16 Dec 2014 02:54:14 -0500 Received: from mail-pd0-f174.google.com ([209.85.192.174]:59667 "EHLO mail-pd0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750857AbaLPHyM (ORCPT ); Tue, 16 Dec 2014 02:54:12 -0500 MIME-Version: 1.0 In-Reply-To: <20141216024210.GB23270@js1304-P5Q-DELUXE> References: <20141210163017.092096069@linux.com> <20141210163033.717707217@linux.com> <20141215080338.GE4898@js1304-P5Q-DELUXE> <20141216024210.GB23270@js1304-P5Q-DELUXE> Date: Tue, 16 Dec 2014 11:54:12 +0400 Message-ID: Subject: Re: [PATCH 3/7] slub: Do not use c->page on free From: Andrey Ryabinin To: Joonsoo Kim Cc: Christoph Lameter , akpm@linuxfoundation.org, rostedt@goodmis.org, LKML , Thomas Gleixner , "linux-mm@kvack.org" , Pekka Enberg , Jesper Dangaard Brouer Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2014-12-16 5:42 GMT+03:00 Joonsoo Kim : > On Mon, Dec 15, 2014 at 08:16:00AM -0600, Christoph Lameter wrote: >> On Mon, 15 Dec 2014, Joonsoo Kim wrote: >> >> > > +static bool same_slab_page(struct kmem_cache *s, struct page *page, void *p) >> > > +{ >> > > + long d = p - page->address; >> > > + >> > > + return d > 0 && d < (1 << MAX_ORDER) && d < (compound_order(page) << PAGE_SHIFT); >> > > +} >> > > + >> > >> > Somtimes, compound_order() induces one more cacheline access, because >> > compound_order() access second struct page in order to get order. Is there >> > any way to remove this? >> >> I already have code there to avoid the access if its within a MAX_ORDER >> page. We could probably go for a smaller setting there. PAGE_COSTLY_ORDER? > > That is the solution to avoid compound_order() call when slab of > object isn't matched with per cpu slab. > > What I'm asking is whether there is a way to avoid compound_order() call when slab > of object is matched with per cpu slab or not. > Can we use page->objects for that? Like this: return d > 0 && d < page->objects * s->size; -- 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/