From: Vince Weaver <vincent.weaver@maine.edu>
Date: Mon, 13 Mar 2017 14:35:11 -0400 (EDT)
To: Peter Zijlstra <peterz@infradead.org>
cc: Tan Xiaojun <tanxiaojun@huawei.com>, 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
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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