From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752213Ab3GHIvP (ORCPT ); Mon, 8 Jul 2013 04:51:15 -0400 Received: from mga14.intel.com ([143.182.124.37]:49878 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751717Ab3GHIvN (ORCPT ); Mon, 8 Jul 2013 04:51:13 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,1019,1363158000"; d="scan'208";a="265321596" Message-ID: <51DA7D77.3000806@intel.com> Date: Mon, 08 Jul 2013 16:51:03 +0800 From: "Yan, Zheng" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 MIME-Version: 1.0 To: Peter Zijlstra CC: linux-kernel@vger.kernel.org, mingo@kernel.org, eranian@google.com, andi@firstfloor.org Subject: Re: [PATCH v2 3/7] perf, x86: Introduce x86 special perf event context References: <1372663387-11754-1-git-send-email-zheng.z.yan@intel.com> <1372663387-11754-4-git-send-email-zheng.z.yan@intel.com> <20130704124148.GI23916@twins.programming.kicks-ass.net> <51D63B43.9050604@intel.com> <20130705124500.GS23916@twins.programming.kicks-ass.net> In-Reply-To: <20130705124500.GS23916@twins.programming.kicks-ass.net> 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 On 07/05/2013 08:45 PM, Peter Zijlstra wrote: > On Fri, Jul 05, 2013 at 11:19:31AM +0800, Yan, Zheng wrote: >> On 07/04/2013 08:41 PM, Peter Zijlstra wrote: >>> It should be *optional*, also wtf is that parent_ctx thing for? >> >> parent_ctx is for the fork() case, used for checking if the callstack feature >> is enabled for the parent task. If yes, clone parent task's LBR stack. >> For the simple program below: > > So there's a problem with all this; contexts aren't strict per task, we > play games with them in perf_event_context_sched_out(). We'd have to > disable that context switch optimization for LBR stack to work and > that's massively expensive. > Sorry, I didn't realize the optimization. I will describe my change in more details in the further. Yan, Zheng > If you actually did that, you again fail for not having mentioned this > in your changelog. > > I'm starting to not want to read patches from you; going through them is > just too much effort, I might as well write the stuff myself :/ >