From mboxrd@z Thu Jan 1 00:00:00 1970 From: Manuel Selva Subject: Re: Does perf randomize the sampling period? Date: Wed, 9 Sep 2015 17:16:12 +0200 Message-ID: <55F04D3C.60908@gmail.com> References: <1769534.mDAXVEGQ5L@milian-kdab2> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wi0-f181.google.com ([209.85.212.181]:38669 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752147AbbIIPQP (ORCPT ); Wed, 9 Sep 2015 11:16:15 -0400 Received: by wiclk2 with SMTP id lk2so25871573wic.1 for ; Wed, 09 Sep 2015 08:16:14 -0700 (PDT) In-Reply-To: <1769534.mDAXVEGQ5L@milian-kdab2> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Milian Wolff , linux-perf-users@vger.kernel.org Regarding perf mem record on Intel platforms, I think that the sampling randomization is ensured by the hardware. ---- Manu On 09/09/2015 05:11 PM, Milian Wolff wrote: > Hey all, > > does perf randomize its sampling intervals/period to prevent pattern effects? > I found https://lkml.org/lkml/2010/3/4/51 but neither the man page on perf > record says anything on that matter, nor does the perf wiki say it's > supported: > > https://perf.wiki.kernel.org/index.php/Tutorial#Period_and_rate > >> There is currently no support for sampling period randomization. > > So is it supported, or not? If it is supported, how do I enable it? Or is this > enabled by default? > > If it is not supported, why so? Is it not important to have? > > Thanks >