Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758739Ab0GPSQP (ORCPT ); Fri, 16 Jul 2010 14:16:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45774 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756269Ab0GPSQO (ORCPT ); Fri, 16 Jul 2010 14:16:14 -0400 Message-ID: <4C40A1BD.4040507@redhat.com> Date: Fri, 16 Jul 2010 21:15:25 +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> In-Reply-To: <4C409F62.6030303@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: 1317 Lines: 35 On 07/16/2010 09:05 PM, H. Peter Anvin wrote: > >> Module loading can certainly take a vmalloc_sync_all() (though I agree >> it's unpleasant). Anything else? >> >> Note perf is not modular at this time, but could be made so with >> preempt/sched notifiers to hook the context switch. >> >> > Actually, module loading is already a performance problem; a lot of > distros load sometimes hundreds of modules on startup, and it's heavily > serialized, so I can see this being desirable to skip. > There aren't that many processes at this time (or there shouldn't be, don't know how fork-happy udev is at this stage), so the sync should be pretty fast. In any case, we can sync only modules that contain NMI handlers. > I really hope noone ever gets the idea of touching user space from an > NMI handler, though, and expecting it to work... > I think the concern here is about an NMI handler's code running in vmalloc space, or is it something else? -- 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/