From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755052AbaE1Rpr (ORCPT ); Wed, 28 May 2014 13:45:47 -0400 Received: from mga02.intel.com ([134.134.136.20]:2986 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754969AbaE1Rpp (ORCPT ); Wed, 28 May 2014 13:45:45 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.98,929,1392192000"; d="scan'208";a="519173267" Date: Wed, 28 May 2014 10:45:45 -0700 From: Andi Kleen To: Peter Zijlstra Cc: Stephane Eranian , "Yan, Zheng" , LKML , "mingo@elte.hu" Subject: Re: [RFC PATCH 6/7] perf, x86: large PEBS interrupt threshold Message-ID: <20140528174545.GN29957@tassilo.jf.intel.com> References: <1401257890-30535-1-git-send-email-zheng.z.yan@intel.com> <1401257890-30535-7-git-send-email-zheng.z.yan@intel.com> <20140528081053.GP11096@twins.programming.kicks-ass.net> <20140528145831.GH29957@tassilo.jf.intel.com> <20140528165144.GK29957@tassilo.jf.intel.com> <20140528171243.GL29957@tassilo.jf.intel.com> <20140528171957.GW30445@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140528171957.GW30445@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > So the window is fairly large for another to slip in, esp if you have a > fast (say inst-ret) and a slow (say br-misp) event. yes, but unless you have really small periods it's still very unlikely that they synchronize, so it will only happen very rarely. And the rare cases won't affect the statistics very much. Even with multi-pebs the min period is 1000, which is several orders of magnitude larger than the typical window. -Andi