Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753104AbZFWJUK (ORCPT ); Tue, 23 Jun 2009 05:20:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751402AbZFWJT7 (ORCPT ); Tue, 23 Jun 2009 05:19:59 -0400 Received: from mail-fx0-f213.google.com ([209.85.220.213]:40994 "EHLO mail-fx0-f213.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751765AbZFWJT6 convert rfc822-to-8bit (ORCPT ); Tue, 23 Jun 2009 05:19:58 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:reply-to:in-reply-to:references:date:message-id :subject:from:to:cc:content-type:content-transfer-encoding; b=FnM0Vd+EoNCoWjQBhaw6s+fMTkfdyOdjYHyRbcdIQS7EQirDstiUMHUOohp0jNOvN0 yoLcvUOJuPNRSKd2axPSNSbFigZXzQJlTbGBlDMgEsevp1Y96Fp3hSA+WA/8lgHJOtVb Xzw8SFhKPjnDSs3tKZHzHnBh+EqziZXUhk2XE= MIME-Version: 1.0 Reply-To: eranian@gmail.com In-Reply-To: <20090623085321.GC23534@ywang-moblin2.bj.intel.com> References: <7c86c4470906221326j6edbf9f3g5d65e96d86aaf7ab@mail.gmail.com> <9F0C1DB20AFA954FA1DA05309350433D7B2584D1@pdsmsx503.ccr.corp.intel.com> <7c86c4470906230045k578bc146wa0e09e4094d937a5@mail.gmail.com> <20090623075959.GA23534@ywang-moblin2.bj.intel.com> <7c86c4470906230127g4f574b61p24f109c7a94c6e39@mail.gmail.com> <7c86c4470906230140p35ce043fw24e0c20651568f31@mail.gmail.com> <20090623085321.GC23534@ywang-moblin2.bj.intel.com> Date: Tue, 23 Jun 2009 11:19:59 +0200 Message-ID: <7c86c4470906230219o23e1b85u7111cc0f527ab906@mail.gmail.com> Subject: Re: perf_counter Atom patch From: stephane eranian To: Yong Wang Cc: "Wang, Yong Y" , Ingo Molnar , Peter Zijlstra , LKML , Paul Mackerras , Andi Kleen Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1958 Lines: 48 On Tue, Jun 23, 2009 at 10:53 AM, Yong Wang wrote: > On Tue, Jun 23, 2009 at 10:40:45AM +0200, stephane eranian wrote: >> Yong, >> >> On Tue, Jun 23, 2009 at 10:27 AM, stephane >> eranian wrote: >> > Hi, >> > >> > On Tue, Jun 23, 2009 at 9:59 AM, Yong Wang wrote: >> >> On Tue, Jun 23, 2009 at 09:45:03AM +0200, stephane eranian wrote: >> >>> >> >>> Unfortunately, I don't have a N270 to compare with your results. >> >>> We need to verify whether or not N270 implements the fixed counters. >> >>> Does it report architected perfmon v3 or v1? >> >>> >> >> >> >> All Atom processors report perfmon v3 as specified in SDM. N270 is no >> >> exception. >> >> >> > V3 does not set a minimal number of fixed counters, could be zero. But >> > that seems >> > odd. Let me ask around. >> > >> Second thought on this: >>        x86_pmu.num_counters_fixed      = >> max((int)edx.split.num_counters_fixed, 3); >> >>         rdmsrl(MSR_CORE_PERF_GLOBAL_CTRL, x86_pmu.intel_ctrl); >> >> >> Forcing num_counter_fixed is not enough, you need to make sure they are actually >> activated in GLOBAL_CTRL, i.e., make sure bits 32-34 are set in intel_ctrl. >> Depending on which machine you're on, the power on value for GLOBAL_CTRL >> changes. The correct value for it should be that ONLY generic counters are on >> by default. >> > > Oh, this might be why fixed counter do not work on my Atom box. I will > look into it. BTW, why should ONLY generic counters be on by default? > Glad you asked. I think, it's for backward compatibility with processors such as Core Duo with architected perfmon v1 which did not have the GLOBAL_* controls. -- 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/