Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753533AbdCMSfX (ORCPT ); Mon, 13 Mar 2017 14:35:23 -0400 Received: from mail-it0-f65.google.com ([209.85.214.65]:33028 "EHLO mail-it0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751320AbdCMSfQ (ORCPT ); Mon, 13 Mar 2017 14:35:16 -0400 From: Vince Weaver X-Google-Original-From: Vince Weaver Date: Mon, 13 Mar 2017 14:35:11 -0400 (EDT) X-X-Sender: vince@macbook-air To: Peter Zijlstra cc: Tan Xiaojun , jolsa@redhat.com, alexander.shishkin@linux.intel.com, eranian@google.com, mingo@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [tip:perf/urgent] perf/core: Fix the perf_cpu_time_max_percent check In-Reply-To: <20170225095117.GU6500@twins.programming.kicks-ass.net> Message-ID: References: <1487829879-56237-1-git-send-email-tanxiaojun@huawei.com> <58B13BFD.2050304@huawei.com> <20170225095117.GU6500@twins.programming.kicks-ass.net> 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: 1085 Lines: 28 On Sat, 25 Feb 2017, Peter Zijlstra wrote: > On Sat, Feb 25, 2017 at 04:10:37PM +0800, Tan Xiaojun wrote: > > > 2)If it is, where we will fix it more appropriate, perf_fuzzer(not set > > 0 or 100) or kernel(limit 1 to 99), or maybe it is the bug of > > hardware(too many hardware interruptions)? > > I think the best would be if the fuzzer would not set 0,100, those are > clearly 'unsafe' settings and you pretty much get to keep the pieces. > > I would like to preserve these settings for people that 'know' what > they're doing and are willing to take the risk, but clearly, when you > take the guard-rails off, things can come apart. sorry for the delay responding, these e-mails ended up in the spam folder somehow. I could add a new "avoid stupid things as root" flag for the perf_fuzzer. Besides this issue, are there other known things to skip? Generally running a fuzzer as root can be a bad idea which is why I don't test that use case very often. I think there were other issues in the past, like certain ftrace combinations being known to lock the system. Vince