From mboxrd@z Thu Jan 1 00:00:00 1970 From: Harald Servat Subject: Re: Sample memory references with at least a given latency? Date: Thu, 05 Feb 2015 12:39:26 +0100 Message-ID: <54D3566E.4010103@bsc.es> References: <54D21524.8010305@bsc.es> <54D22AB8.4060607@bsc.es> <54D354F0.2090405@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mao.bsc.es ([84.88.52.34]:48248 "EHLO opsmail01.bsc.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752004AbbBELj2 (ORCPT ); Thu, 5 Feb 2015 06:39:28 -0500 In-Reply-To: <54D354F0.2090405@gmail.com> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Manuel Selva Cc: "linux-perf-users@vger.kernel.org" Hello, On 05/02/15 12:33, Manuel Selva wrote: > Hi Harald, > > You are right, the perf mem tool dosn't support stting the latency > threshold. It should be a very easy first contribution to kernel for > myself ;-) that would be great. If I had some spare time & a machine to mess a bit, I'd gladly help you. BTW, do you know if there's any alternative for developing the kernel? > Regarding the timestamp, I nver need such information, but as you said > you can't tll to the hardware (on Intel I mean) to record it along with > processor state information. I don't know how th kernel part of perf > configure PEBS, but why would the kernel pay the overhead of an > interrupt by using 1 slot buffers ? Only for recording timestamp ? Personally, I play with time-stamped trace-files and find capturing the time-stamp extremely important! Andi Kleen (also from this list) confirmed this (1 slot buffer) but he didn't mention the exact reason. Still, and let me insist, this is perfect for my purposes so I'm ok with it. See previous mails from this ML: http://article.gmane.org/gmane.linux.kernel.perf.user/1398/match=information+regarding+perf+tool http://article.gmane.org/gmane.linux.kernel.perf.user/1375/match=information+regarding+perf+tool Regards. > ---- > Manu > > On 02/04/2015 03:20 PM, Harald Servat wrote: >> >> Hello Manuel, >> >> I'm running Linux 3.11 but I don't see a way to setup the latency >> threshold there. My option flags include: >> >> -t, --type= >> -D, --dump-raw-samples= >> -x, --field-separator >> -C, --cpu-list >> >> so I guess that this option is not implemented in perf (at least on >> 3.11). So I need to capture all the samples and then discard those that >> surpass that threshold. >> >> Going back into your example, is it possible to capture / show the >> timestamp for the captured samples? I've seen the Intel documentation, >> and there aren't timestamps in PEBS entries so that may require >> additional work. IIRC, someone of the list told me that perf allocates a >> 1-entry PEBS buffer so every time PEBS fills it, perf somehow gets an >> interrupt indicating that it has to flush it. This way, perf can >> attribute a timestamp to that sample also. >> >> Thank you very much! >> >> >> On 04/02/15 15:00, Manuel Selva wrote: >>> Hi Harald, >>> >>> Yes you can with the "perf mem" tool. It has been introduced in kernel >>> 3.10 (correct me if I am wrong, not very sure about that). It's built on >>> top of perf mem record and perf mem report but hide for you the >>> complxity of choosing the memory events . See "man perf mem" for th >>> details. >>> >>> ---------- >>> Manuel >>> >>> >>> >>> 2015-02-04 13:48 GMT+01:00 Harald Servat >> >: >>> >>> Hello list, >>> >>> is there any way to configure perf to sample memory references >>> through PEBS and enable the Load Latency Performance Monitoring >>> Facility (section 18.7.1.2 from the Intel 64 and IA-32 Architectures >>> Software Developer's Manual). >>> >>> Thank you very much in advance. >>> >>> WARNING / LEGAL TEXT: This message is intended only for the use of >>> the >>> individual or entity to which it is addressed and may contain >>> information which is privileged, confidential, proprietary, or >>> exempt >>> from disclosure under applicable law. If you are not the intended >>> recipient or the person responsible for delivering the message to >>> the >>> intended recipient, you are strictly prohibited from disclosing, >>> distributing, copying, or in any way using this message. If you have >>> received this communication in error, please notify the sender and >>> destroy and delete any copies you may have received. >>> >>> http://www.bsc.es/disclaimer >>> -- >>> To unsubscribe from this list: send the line "unsubscribe >>> linux-perf-users" in >>> the body of a message to majordomo@vger.kernel.org >>> >>> More majordomo info at http://vger.kernel.org/__majordomo-info.html >>> >>> >>> >> >> >> WARNING / LEGAL TEXT: This message is intended only for the use of the >> individual or entity to which it is addressed and may contain >> information which is privileged, confidential, proprietary, or exempt >> from disclosure under applicable law. If you are not the intended >> recipient or the person responsible for delivering the message to the >> intended recipient, you are strictly prohibited from disclosing, >> distributing, copying, or in any way using this message. 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