From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: Weird instruction profiling Date: Wed, 18 Feb 2015 16:46:25 -0700 Message-ID: <54E52451.4030303@gmail.com> References: <87zj8bvzqn.fsf@tassilo.jf.intel.com> <54E5214B.5060408@gmail.com> <20150218233836.GB823@two.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ie0-f173.google.com ([209.85.223.173]:41848 "EHLO mail-ie0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751901AbbBRXq0 (ORCPT ); Wed, 18 Feb 2015 18:46:26 -0500 Received: by iecrd18 with SMTP id rd18so5478412iec.8 for ; Wed, 18 Feb 2015 15:46:25 -0800 (PST) In-Reply-To: <20150218233836.GB823@two.firstfloor.org> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Andi Kleen Cc: Brendan Gregg , "linux-perf-use." On 2/18/15 4:38 PM, Andi Kleen wrote: > On Wed, Feb 18, 2015 at 04:33:31PM -0700, David Ahern wrote: >> On 2/18/15 11:30 AM, Andi Kleen wrote: >> >>>> I think Andi mentioned this to me last year -- that instruction >>>> profiling was no longer reliable. >>> >>> It never was. >> >> Why is that? What about profiling with other hardware counters? > > Practically all profiling has skid of some form. ok, so you meant that only in the context of skid meaning the hit instruction is off a few (ie., squint backwards at the annotate output). David