Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757893AbcLOJeU (ORCPT ); Thu, 15 Dec 2016 04:34:20 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:46738 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757875AbcLOJeS (ORCPT ); Thu, 15 Dec 2016 04:34:18 -0500 Date: Thu, 15 Dec 2016 10:31:27 +0100 (CET) From: Thomas Gleixner To: Roland Scheidegger cc: LKML , x86@kernel.org, Peter Zijlstra , Borislav Petkov , Bruce Schlobohm , Kevin Stanton , Allen Hung Subject: Re: [patch 0/2] tsc/adjust: Cure suspend/resume issues and prevent TSC deadline timer irq storm In-Reply-To: <036e72e3-3686-4f69-eea5-c41747ef0019@hispeed.ch> Message-ID: References: <20161213131115.764824574@linutronix.de> <33d4286c-3f77-1274-34b7-bc62d2c146a4@hispeed.ch> <357e0a0f-af6b-2a8e-2af0-b05652ccbb30@hispeed.ch> <036e72e3-3686-4f69-eea5-c41747ef0019@hispeed.ch> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 877 Lines: 21 On Wed, 14 Dec 2016, Roland Scheidegger wrote: > Am 14.12.2016 um 22:40 schrieb Thomas Gleixner: > > And the whole mess stems from the fact that the deadline is not as one > > would expect simply compared against the sum of the counter and the adjust > > MSR. > Why would it be compared against the sum? As far as I can tell the adjust > value should never come into play when using deadline timer (other than > indirectly because the TSC would change). See the SDM. It suggests that the deadline is compared to the TSC value. I don't care how it is implemented, but I very much care about it being documented in the way it is implemented, which is obviously not the case. And even if the adjust value is subtracted once when the timer is armed the whole thing should not blow up due to 32bit/sign extension bugs or whatever they decided to cobble together. Thanks, tglx