From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752211AbaBKQob (ORCPT ); Tue, 11 Feb 2014 11:44:31 -0500 Received: from mga09.intel.com ([134.134.136.24]:6589 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751566AbaBKQoa (ORCPT ); Tue, 11 Feb 2014 11:44:30 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.95,826,1384329600"; d="scan'208";a="481659378" Message-ID: <52FA5366.3020007@linux.intel.com> Date: Tue, 11 Feb 2014 08:44:22 -0800 From: Dave Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Peter Zijlstra CC: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, dzickus@redhat.com, linux-tip-commits@vger.kernel.org Subject: Re: [tip:perf/core] x86/nmi: Push duration printk() to irq context References: <52F9021C.1030801@linux.intel.com> <20140211150116.GO27965@twins.programming.kicks-ass.net> In-Reply-To: <20140211150116.GO27965@twins.programming.kicks-ass.net> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/11/2014 07:01 AM, Peter Zijlstra wrote: > - irq_work_queue(&perf_duration_work); > + if (!irq_work_queue(&perf_duration_work)) { > + early_printk("perf interrupt took too long (%lld > %lld), lowering " > + "kernel.perf_event_max_sample_rate to %d\n", > + avg_local_sample_len, allowed_ns >> 1, > + sysctl_perf_event_sample_rate); > + } > } That's a cool trick. Works for me.