Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752308AbaLROlh (ORCPT ); Thu, 18 Dec 2014 09:41:37 -0500 Received: from mail-ob0-f175.google.com ([209.85.214.175]:37137 "EHLO mail-ob0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbaLROlg (ORCPT ); Thu, 18 Dec 2014 09:41:36 -0500 MIME-Version: 1.0 In-Reply-To: References: <20141210163017.092096069@linux.com> <20141215075933.GD4898@js1304-P5Q-DELUXE> Date: Thu, 18 Dec 2014 23:41:35 +0900 Message-ID: Subject: Re: [PATCH 0/7] slub: Fastpath optimization (especially for RT) V1 From: Joonsoo Kim To: Christoph Lameter Cc: Joonsoo Kim , akpm@linuxfoundation.org, Steven Rostedt , LKML , Thomas Gleixner , Linux Memory Management List , 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 2014-12-18 1:10 GMT+09:00 Christoph Lameter : > On Wed, 17 Dec 2014, Joonsoo Kim wrote: > >> + do { >> + tid = this_cpu_read(s->cpu_slab->tid); >> + c = this_cpu_ptr(s->cpu_slab); >> + } while (IS_ENABLED(CONFIG_PREEMPT) && unlikely(tid != c->tid)); > > > Assembly code produced is a bit weird. I think the compiler undoes what > you wanted to do: I checked my compiled code and it seems to be no problem. gcc (Ubuntu 4.8.2-19ubuntu1) 4.8.2 Thanks. > 46fb: 49 8b 1e mov (%r14),%rbx rbx = c =s->cpu_slab? > 46fe: 65 4c 8b 6b 08 mov %gs:0x8(%rbx),%r13 r13 = tid > 4703: e8 00 00 00 00 callq 4708 ?? > 4708: 89 c0 mov %eax,%eax ?? > 470a: 48 03 1c c5 00 00 00 add 0x0(,%rax,8),%rbx ?? > 4711: 00 > 4712: 4c 3b 6b 08 cmp 0x8(%rbx),%r13 tid == c->tid > 4716: 49 89 d8 mov %rbx,%r8 > 4719: 75 e0 jne 46fb > -- 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/