From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f45.google.com (mail-pa0-f45.google.com [209.85.220.45]) by kanga.kvack.org (Postfix) with ESMTP id 5B61F6B0032 for ; Thu, 15 Jan 2015 22:51:09 -0500 (EST) Received: by mail-pa0-f45.google.com with SMTP id lf10so21665799pab.4 for ; Thu, 15 Jan 2015 19:51:09 -0800 (PST) Received: from cdptpa-oedge-vip.email.rr.com (cdptpa-outbound-snat.email.rr.com. [107.14.166.225]) by mx.google.com with ESMTP id gz10si4041533pbd.94.2015.01.15.19.51.07 for ; Thu, 15 Jan 2015 19:51:08 -0800 (PST) Date: Thu, 15 Jan 2015 22:51:30 -0500 From: Steven Rostedt Subject: Re: [PATCH v2 1/2] mm/slub: optimize alloc/free fastpath by removing preemption on/off Message-ID: <20150115225130.00c0c99a@grimm.local.home> In-Reply-To: References: <1421307633-24045-1-git-send-email-iamjoonsoo.kim@lge.com> <20150115171634.685237a4.akpm@linux-foundation.org> <20150115203045.00e9fb73@grimm.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Andrew Morton , Joonsoo Kim , Pekka Enberg , David Rientjes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jesper Dangaard Brouer , Thomas Gleixner , Peter Zijlstra On Thu, 15 Jan 2015 21:27:14 -0600 (CST) Christoph Lameter wrote: > > The %gs register is not used since the address of the per cpu area is > available as one of the first fields in the per cpu areas. Have you disassembled your code? Looking at put_cpu_partial() from 3.19-rc3 where it does: oldpage = this_cpu_read(s->cpu_slab->partial); I get: mov %gs:0x18(%rax),%rdx Looks to me that %gs is used. I haven't done benchmarks in a while, so perhaps accessing the %gs segment isn't as expensive as I saw it before. I'll have to profile function tracing on my i7 and see where things are slow again. -- Steve -- 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