From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f175.google.com (mail-ig0-f175.google.com [209.85.213.175]) by kanga.kvack.org (Postfix) with ESMTP id 30A9A6B0032 for ; Fri, 16 Jan 2015 08:41:04 -0500 (EST) Received: by mail-ig0-f175.google.com with SMTP id r2so3366504igi.2 for ; Fri, 16 Jan 2015 05:41:03 -0800 (PST) Received: from mail-ie0-x230.google.com (mail-ie0-x230.google.com. [2607:f8b0:4001:c03::230]) by mx.google.com with ESMTPS id ac4si1299757igd.20.2015.01.16.05.41.01 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 16 Jan 2015 05:41:02 -0800 (PST) Received: by mail-ie0-f176.google.com with SMTP id tr6so20690593ieb.7 for ; Fri, 16 Jan 2015 05:41:01 -0800 (PST) Message-ID: <1421415659.11734.131.camel@edumazet-glaptop2.roam.corp.google.com> Subject: Re: [PATCH v2 1/2] mm/slub: optimize alloc/free fastpath by removing preemption on/off From: Eric Dumazet Date: Fri, 16 Jan 2015 05:40:59 -0800 In-Reply-To: <20150115230749.5d73ad49@grimm.local.home> References: <1421307633-24045-1-git-send-email-iamjoonsoo.kim@lge.com> <20150115171634.685237a4.akpm@linux-foundation.org> <20150115203045.00e9fb73@grimm.local.home> <20150115225130.00c0c99a@grimm.local.home> <20150115230749.5d73ad49@grimm.local.home> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Steven Rostedt Cc: Christoph Lameter , 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, 2015-01-15 at 23:07 -0500, Steven Rostedt wrote: > On Thu, 15 Jan 2015 21:57:58 -0600 (CST) > Christoph Lameter wrote: > > > > I get: > > > > > > mov %gs:0x18(%rax),%rdx > > > > > > Looks to me that %gs is used. > > > > %gs is used as a segment prefix. That does not add significant cycles. > > Retrieving the content of %gs and loading it into another register > > would be expensive in terms of cpu cycles. > > OK, maybe that's what I saw in my previous benchmarks. Again, that was > a while ago. I made same observation about 3 years ago, on old cpus. -- 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