From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60AE4C3A5A1 for ; Wed, 28 Aug 2019 16:29:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0A75A20644 for ; Wed, 28 Aug 2019 16:29:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="DOSB80d1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726706AbfH1Q3E (ORCPT ); Wed, 28 Aug 2019 12:29:04 -0400 Received: from merlin.infradead.org ([205.233.59.134]:49412 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726440AbfH1Q3E (ORCPT ); Wed, 28 Aug 2019 12:29:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=znSnT974Vl4Y8YOZ/9zd4iEg86qp19ImyyCFqmd1BbA=; b=DOSB80d13xppS27hBHrvl2LGe VXKSlGeI0uYu7QVgeyr5PX8IaC2NTe40s1TTceDqN1HVNJTeEoMTyVhRQHTAqkvvxAcgW3DjUO0aK 1n6pm9QlBtX9AsCXmGF2JM/mSUCGRl09Az7xCAxD/pjQel/Xz1g00Pi2sec9vPurYBbB965WlYEDk ytUP37p1XyezPqwXTOnBy/W3vJ5+4KjIRIoz70DMvMK/0gssE7HjXOZVs3poeaD91/xafISQlala2 KSzTixuF1/6vF/dPef4UDuUO+3SFNB5UUD9qvbkCxYCTmUzahopr3pBoojjoOD8YULatUEGRsg7/I vYkookxeA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1i30oc-00066Y-Pm; Wed, 28 Aug 2019 16:28:59 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 1C41A300B83; Wed, 28 Aug 2019 18:28:23 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 14FAE20C3AB21; Wed, 28 Aug 2019 18:28:57 +0200 (CEST) Date: Wed, 28 Aug 2019 18:28:57 +0200 From: Peter Zijlstra To: Andi Kleen Cc: kan.liang@linux.intel.com, acme@kernel.org, mingo@redhat.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, jolsa@kernel.org, eranian@google.com, alexander.shishkin@linux.intel.com Subject: Re: [RESEND PATCH V3 3/8] perf/x86/intel: Support hardware TopDown metrics Message-ID: <20190828162857.GO2332@hirez.programming.kicks-ass.net> References: <20190826144740.10163-1-kan.liang@linux.intel.com> <20190826144740.10163-4-kan.liang@linux.intel.com> <20190828151921.GD17205@worktop.programming.kicks-ass.net> <20190828161754.GP5447@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190828161754.GP5447@tassilo.jf.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 28, 2019 at 09:17:54AM -0700, Andi Kleen wrote: > > This really doesn't make sense to me; if you set FIXED_CTR3 := 0, you'll > > never trigger the overflow there; this then seems to suggest the actual > > The 48bit counter might overflow in a few hours. Sure; the point is? Kan said it should not be too big; a full 48bit wrap around must be too big or nothing is.