From mboxrd@z Thu Jan 1 00:00:00 1970 From: Manuel Selva Subject: Re: Understanding perf mem -t load results Date: Wed, 25 Dec 2013 11:25:44 +0100 Message-ID: <52BAB2A8.1040709@gmail.com> References: <1776760155.10395562.1386857164818.JavaMail.root@insa-lyon.fr> <877gb5vmmn.fsf@tassilo.jf.intel.com> <52AE2721.8020501@insa-lyon.fr> <20131215234548.GP21717@two.firstfloor.org> <20131224021822.GH20765@two.firstfloor.org> <52B93352.2030909@gmail.com> <20131224072813.GI20765@two.firstfloor.org> <52B93B01.4020305@gmail.com> <20131224212728.GK20765@two.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-we0-f176.google.com ([74.125.82.176]:41038 "EHLO mail-we0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751665Ab3LYKZr (ORCPT ); Wed, 25 Dec 2013 05:25:47 -0500 Received: by mail-we0-f176.google.com with SMTP id p61so6455454wes.7 for ; Wed, 25 Dec 2013 02:25:46 -0800 (PST) In-Reply-To: <20131224212728.GK20765@two.firstfloor.org> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Andi Kleen Cc: linux-perf-users@vger.kernel.org On 12/24/2013 10:27 PM, Andi Kleen wrote: >> I checked what can be measured with the offcore facility. I can ask >> to count remote memory accesses, but now I am not sure PEBS is >> enable for these events. If the answer is no, I can't accurately >> identify remote memory accesses with offcore events ? As a >> consequence I am wondering if there is a way to do such thing ? > > The OFFCORE events are not PEBS enabled. Ok, you confirm what I read in the Intel SDM. However the memory PEBS > events report the same information (with some limitations) in > the PEBS record (and perf reports this information) By memory PEBS events, do you mean the following events ? MEM_LOAD_RETIRED.L1D_MISS MEM_LOAD_RETIRED.L1D_LINE_MISS MEM_LOAD_RETIRED.L2_MISS MEM_LOAD_RETIRED.L2_LINE_MISS MEM_LOAD_RETIRED.DTLB_MISS I can't profile memory accesses with these events, isn't it ? What do you mean by perf reports this infomation, which perf tool ? > > In general you cannot accurately profile all memory accesses. Does it means that the perf mem record tool is reporting wrong values concerning the source of the event ? (I checked that this tool use the load latency event with PEBS and you said that the IP reported by this uncore event is not always the correct one ?) Thanks, ---- Manu