Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751861AbaFENQu (ORCPT ); Thu, 5 Jun 2014 09:16:50 -0400 Received: from mail-ob0-f171.google.com ([209.85.214.171]:57833 "EHLO mail-ob0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751460AbaFENQs (ORCPT ); Thu, 5 Jun 2014 09:16:48 -0400 MIME-Version: 1.0 In-Reply-To: <20140605125929.GH6758@twins.programming.kicks-ass.net> References: <1401917658-26065-1-git-send-email-eranian@google.com> <1401917658-26065-10-git-send-email-eranian@google.com> <20140605125022.GF6758@twins.programming.kicks-ass.net> <20140605125929.GH6758@twins.programming.kicks-ass.net> Date: Thu, 5 Jun 2014 15:16:47 +0200 Message-ID: Subject: Re: [PATCH 9/9] perf/x86: add syfs entry to disable HT bug workaround From: Stephane Eranian To: Peter Zijlstra Cc: Matt Fleming , LKML , "mingo@elte.hu" , "ak@linux.intel.com" , Jiri Olsa , "Yan, Zheng" , Maria Dimakopoulou Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 5, 2014 at 2:59 PM, Peter Zijlstra wrote: > On Thu, Jun 05, 2014 at 02:55:05PM +0200, Stephane Eranian wrote: >> On Thu, Jun 5, 2014 at 2:50 PM, Peter Zijlstra wrote: >> > On Thu, Jun 05, 2014 at 12:16:01PM +0100, Matt Fleming wrote: >> >> On 5 June 2014 11:19, Stephane Eranian wrote: >> >> > How would you know that you have a uniform workload from inside >> >> > the kernel? >> >> >> >> That's what I'm asking you ;-) >> >> >> >> >> Does cpu_sibling_map not give you some indication of whether HT is >> >> >> enabled? I think the topology_thread_cpumask() is the topology API for >> >> >> that. But I could most definitely be wrong. Hopefully someone on the >> >> >> Cc list will know. >> >> >> >> >> > Remember trying some of that, but when perf_event is initialized, those >> >> > masks are not yet setup properly. >> >> >> >> Oh, bummer. >> > >> > So we init perf very early to get nmi-watchdog up and running, but >> > there's no reason you cannot register a second initcall later and flip >> > the switch from it there. >> >> and what initcall would that be? > > Pretty much anything !early_initcall() is ran after SMP bringup iirc. Ok, we can try this. Need to check the impact on NMI watchdog if already active. -- 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/