Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754214Ab0AENnP (ORCPT ); Tue, 5 Jan 2010 08:43:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753186Ab0AENnO (ORCPT ); Tue, 5 Jan 2010 08:43:14 -0500 Received: from casper.infradead.org ([85.118.1.10]:53965 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751770Ab0AENnO (ORCPT ); Tue, 5 Jan 2010 08:43:14 -0500 Date: Tue, 5 Jan 2010 05:45:36 -0800 From: Arjan van de Ven To: Peter Zijlstra Cc: "Paul E. McKenney" , Peter Zijlstra , KAMEZAWA Hiroyuki , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "minchan.kim@gmail.com" , cl@linux-foundation.org, "hugh.dickins" , Nick Piggin , Ingo Molnar , Linus Torvalds , Peter Zijlstra Subject: Re: [RFC][PATCH 6/8] mm: handle_speculative_fault() Message-ID: <20100105054536.44bf8002@infradead.org> In-Reply-To: <20100104182813.753545361@chello.nl> References: <20100104182429.833180340@chello.nl> <20100104182813.753545361@chello.nl> Organization: Intel X-Mailer: Claws Mail 3.7.3 (GTK+ 2.16.6; i586-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 927 Lines: 24 On Mon, 04 Jan 2010 19:24:35 +0100 Peter Zijlstra wrote: > Generic speculative fault handler, tries to service a pagefault > without holding mmap_sem. while I appreciate the goal of reducing contention on this lock... wouldn't step one be to remove the page zeroing from under this lock? that's by far (easily by 10x I would guess) the most expensive thing that's done under the lock, and I would expect a first order of contention reduction just by having the zeroing of a page not done under the lock... -- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org -- 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/