From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754108Ab1HKVSW (ORCPT ); Thu, 11 Aug 2011 17:18:22 -0400 Received: from merlin.infradead.org ([205.233.59.134]:51089 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753808Ab1HKVSV convert rfc822-to-8bit (ORCPT ); Thu, 11 Aug 2011 17:18:21 -0400 Subject: Re: [PATCH v6 2/2] Output stall data in debugfs From: Peter Zijlstra To: Alex Neronskiy Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Don Zickus , Mandeep Singh Baines Date: Thu, 11 Aug 2011 23:17:55 +0200 In-Reply-To: References: <1312999364-21104-1-git-send-email-zakmagnus@chromium.org> <1312999364-21104-2-git-send-email-zakmagnus@chromium.org> <1313091323.8491.30.camel@twins> <1313094223.26866.15.camel@twins> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.0.2- Message-ID: <1313097475.26866.18.camel@twins> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2011-08-11 at 13:31 -0700, Alex Neronskiy wrote: > > > I mean, we're at the point where a PREEMPT=y kernel has a pretty decent > > latency and the PREEMPT_RT kernels live at ~30us. So wth are you > > measuring? > Well, not all kernels have PREEMPT. Chromebook kernels don't, for example. Can one infer from that statement that the purpose is trying to measure non preempt latency? Why not use the tracer build for that purpose? Still the watchdog ticks at 1s intervals or so, anything that takes that long, even on voluntary preemption kernels is quite insane.