From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751986Ab3LKDDh (ORCPT ); Tue, 10 Dec 2013 22:03:37 -0500 Received: from szxga02-in.huawei.com ([119.145.14.65]:55178 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751893Ab3LKDDe (ORCPT ); Tue, 10 Dec 2013 22:03:34 -0500 Message-ID: <52A7D5E5.3070704@huawei.com> Date: Wed, 11 Dec 2013 11:03:01 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: Howard Chu CC: Linux Kernel Mailing List Subject: Re: sched: RT throttling activated, 3.12.3 References: <52A7D512.5050801@symas.com> In-Reply-To: <52A7D512.5050801@symas.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.135.68.215] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2013/12/11 10:59, Howard Chu wrote: > I just upgraded a system from a 3.5 kernel to 3.12.3 and attempted to run some new benchmarks on it. I see my test program ramps up in CPU usage for a few seconds and then it gradually tails off. There's nothing obvious in the user code to trigger this behavior, so I check dmesg, and see this: > > [ 55.037057] JFS: nTxBlock = 8192, nTxLock = 65536 > [163591.807470] perf samples too long (2758 > 2500), lowering kernel.perf_event_max_sample_rate to 50000 > [164061.362762] perf samples too long (5204 > 5000), lowering kernel.perf_event_max_sample_rate to 25000 > [167969.339513] [sched_delayed] sched: RT throttling activated > [182741.484637] perf samples too long (294588 > 10000), lowering kernel.perf_event_max_sample_rate to 12500 > [182741.484726] INFO: NMI handler (perf_event_nmi_handler) took too long to run: 36.665 msecs > [182822.633084] perf samples too long (292359 > 20000), lowering kernel.perf_event_max_sample_rate to 6250 > [182905.606119] perf samples too long (290291 > 40000), lowering kernel.perf_event_max_sample_rate to 3250 > [199384.293514] perf samples too long (288142 > 76923), lowering kernel.perf_event_max_sample_rate to 1750 > [208507.301027] perf samples too long (285964 > 142857), lowering kernel.perf_event_max_sample_rate to 1000 > [208528.976208] perf samples too long (283799 > 250000), lowering kernel.perf_event_max_sample_rate to 500 > > Why is the kernel throttling my server? > Because that is the default setting of the kernel. lxc34:/proc/sys/kernel # cat sched_rt_period_us 1000000 lxc34:/proc/sys/kernel # cat sched_rt_runtime_us 950000