Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754857Ab3GJW1B (ORCPT ); Wed, 10 Jul 2013 18:27:01 -0400 Received: from prod-mail-xrelay07.akamai.com ([72.246.2.115]:40302 "EHLO prod-mail-xrelay07.akamai.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754259Ab3GJW1A (ORCPT ); Wed, 10 Jul 2013 18:27:00 -0400 Message-ID: <51DDDFB3.3020004@akamai.com> Date: Wed, 10 Jul 2013 18:26:59 -0400 From: Jason Baron User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130330 Thunderbird/17.0.5 MIME-Version: 1.0 To: Jiri Kosina CC: Masami Hiramatsu , Steven Rostedt , "H. Peter Anvin" , "linux-kernel@vger.kernel.org" , mathieu.desnoyers@efficios.com Subject: Re: [RFC] [PATCH 0/2] x86: make jump labels use int3-based breakpoint instead of stop_machine() References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1393 Lines: 38 On 07/10/2013 04:25 PM, Jiri Kosina wrote: > Hi, > > this is a resurrection of a few years old idea to have jump labels use > synchronization based on int3 breakpoint rather than relying on > stop_machine() with all the consequences. > > ftrace has been doing exactly this kind of patching for year since > 08d636b6 ("ftrace/x86: Have arch x86_64 use breakpoints instead of stop > machine"). > > This patchset first introduces generic text_poke_bp() that provides means > to perform this method of patching in parallel to text_poke_smp(), and > then converts x86 jump label code to use it. > > If this is merged, I'll do a followup patch converting ftrace to use this > infrastructure as well, as it's doing the same thing in principle already. > > Comments welcome. > Cool. This definitely an area I've wanted to improve with jump labels. Perhaps, ftrace should be considered at this point to make sure the interface is suitable for both callers? Also, I wonder if its worth batching up updates. For example, right now we simply update each call-site one at a time even if its associated with the same control variable. Thanks, -Jason -- 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/