From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751487AbdAYPdL (ORCPT ); Wed, 25 Jan 2017 10:33:11 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:46946 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750711AbdAYPdK (ORCPT ); Wed, 25 Jan 2017 10:33:10 -0500 Date: Wed, 25 Jan 2017 16:33:01 +0100 From: Peter Zijlstra To: kan.liang@intel.com Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, alexander.shishkin@linux.intel.com, eranian@google.com, ak@linux.intel.com Subject: Re: [PATCH 2/2] perf,core: use parent avg sample period as child initial period Message-ID: <20170125153301.GQ6500@twins.programming.kicks-ass.net> References: <1484745662-15928-1-git-send-email-kan.liang@intel.com> <1484745662-15928-3-git-send-email-kan.liang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1484745662-15928-3-git-send-email-kan.liang@intel.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 18, 2017 at 08:21:02AM -0500, kan.liang@intel.com wrote: > From: Kan Liang > > perf brings additional overhead when monitoring the task which > frequently generates child task. > > When inheriting a event from parent task to child task, the > sample_period of original parent event (parent_event->parent) will be > assigned to child event as its initial period, which is usually the > default sample_period 1. Why is that mostly 1? I would expect the parent event's sample_period to ramp up as well.