Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759115Ab0GPTk4 (ORCPT ); Fri, 16 Jul 2010 15:40:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39721 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759101Ab0GPTkz (ORCPT ); Fri, 16 Jul 2010 15:40:55 -0400 Message-ID: <4C40B57A.1090107@redhat.com> Date: Fri, 16 Jul 2010 22:39:38 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.10) Gecko/20100621 Fedora/3.0.5-1.fc13 Thunderbird/3.0.5 MIME-Version: 1.0 To: "H. Peter Anvin" CC: Mathieu Desnoyers , LKML , Linus Torvalds , Andrew Morton , Ingo Molnar , Peter Zijlstra , Steven Rostedt , Steven Rostedt , Frederic Weisbecker , Thomas Gleixner , Christoph Hellwig , Li Zefan , Lai Jiangshan , Johannes Berg , Masami Hiramatsu , Arnaldo Carvalho de Melo , Tom Zanussi , KOSAKI Motohiro , Andi Kleen , akpm@osdl.org, Jeremy Fitzhardinge , "Frank Ch. Eigler" Subject: Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault References: <20100714154923.947138065@efficios.com> <20100714155804.252253097@efficios.com> <4C405078.20707@redhat.com> <20100716144927.GA22516@Krystal> <4C408D0C.5050709@redhat.com> <20100716165855.GA3836@Krystal> <4C409CBA.1050709@redhat.com> <4C409F62.6030303@zytor.com> <4C40A1BD.4040507@redhat.com> <20100716182240.GA23215@Krystal> <4C40A5A0.3010107@redhat.com> <4C40B324.4040907@zytor.com> In-Reply-To: <4C40B324.4040907@zytor.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1042 Lines: 28 On 07/16/2010 10:29 PM, H. Peter Anvin wrote: > On 07/16/2010 11:32 AM, Avi Kivity wrote: > >> How long would vmalloc_sync_all take with a few thousand mm_struct take? >> >> We share the pmds, yes? So it's a few thousand memory accesses. The >> direct impact is probably negligible, compared to actually loading the >> module from disk. All we need is to make sure the locking doesn't slow >> down unrelated stuff. >> >> > It's not the memory accesses, it's the need to synchronize all the CPUs. > I'm missing something. Why do we need to sync all cpus? the vmalloc_sync_all() I'm reading doesn't. Even if we do an on_each_cpu() somewhere, it isn't the end of the world. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain. -- 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/