From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755400Ab0KZRQu (ORCPT ); Fri, 26 Nov 2010 12:16:50 -0500 Received: from mail-ey0-f174.google.com ([209.85.215.174]:50745 "EHLO mail-ey0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752479Ab0KZRQt (ORCPT ); Fri, 26 Nov 2010 12:16:49 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:content-transfer-encoding :in-reply-to:user-agent; b=xsswk+JrI+HNkzMGGvHc+39/nRz0opCvYOTtHWrs1oJO+czuNi1S3VjawHl3C2uz+3 DjTwMNBIJNKmaIbEhEc1Z/oey/INuon+2znyxKCBF5riC2aRIlMsYhJ87cJ824Sx5jES x2O1i6owUBVoGnD1Z3VnPrjIqGKTM3lvlsTP0= Date: Fri, 26 Nov 2010 20:16:42 +0300 From: Cyrill Gorcunov To: Stephane Eranian Cc: Ingo Molnar , LKML , ming.m.lin@intel.com, peterz@infradead.org Subject: Re: [rfc 1/3] perf, x86: P4 PMU - describe config format Message-ID: <20101126171642.GB5620@lenovo> References: <20101126152744.GA5620@lenovo> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 26, 2010 at 05:22:51PM +0100, Stephane Eranian wrote: > On Fri, Nov 26, 2010 at 4:27 PM, Cyrill Gorcunov wrote: > > On Fri, Nov 26, 2010 at 02:54:39PM +0100, Stephane Eranian wrote: > > ... > >> > > >> > No, single thread mode means _any_ single thread is running, > >> > Stephane I'll describe some more a bit later (as only reach home), > >> > ok? > >> > >> From the manual: > >> > >> 00 — None. Count only when neither logical processor is active. > >> 01 — Single. Count only when one logical processor is active (either 0 or 1). > >> 10 — Both. Count only when both logical processors are active. > >> 11 — Any. Count when either logical processor is active. > >> > >> In per-thread mode, you won't hit 00. I suspect you want to > >> disallow 01, 10 (or CAP_SYS_ADMIN). Otherwise, you want > >> to force 11, i.e., can't figure out what's going on in the other > >> HT thread. > >> > > > >  No ;) The key moment here that this flags are related to _activity_ of > > logical thread and I guess they were introduced just to allow measuring > > if user-space application does win from using HT or not (since for > > some loads the HT simply drops the perfomance). > > > > I think what they call 'logical CPU' is what the kernel calls CPU. yes > So I think bits 16-17 are used if you want to measure on CPU0 only > when CPU1 (assume both share the same physical core) is active > or inactive or don't care. You're right that I believe this mode was > introduced to measure the level of concurrency between HT > thread (logical CPUs). but "single thread mode" measures the event if *any* thread is active at a time, if we would assume that your assumption is right -- there would be no need for T1_OS/T1_USR. So I must admit I'm confused, the Oprofile do things simplier -- it just sets "thread any" ;) > > In architectural perfmon the .any modifier is slightly different. > It indicates whether you want to measure only yourself or both > threads (regardless of the state of the other HT thread). In other > words, it is not because .any=1 that the event counts ONLY when > both threads (logical CPUs) are active. > ... Stephane, could you do a test? We need a pinned event which would be running on say cpu0 only and if you set P4_CCCR_THREAD_SINGLE in CCCR and event would be still incrementing -- this mean my theory is correct and this "thread" field means "when" to count, if not -- you're right and "thread" field means "where" instead. Cyrill