linux-kernel - Re: [RFC PATCH] perf/stat: Add --disable-hwdt

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Message-ID: <20170206124447.GA12772@gmail.com>
Date:   Mon, 6 Feb 2017 13:44:48 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Robert Richter <rric@...nel.org>,
        Vince Weaver <vince@...ter.net>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] perf/stat: Add --disable-hwdt


* Borislav Petkov <bp@...en8.de> wrote:

> On Mon, Feb 06, 2017 at 01:22:31PM +0100, Ingo Molnar wrote:
> > Looks sensible, and I'd in fact make this the new default behavior (if root runs 
> > perf stat) - i.e. add a flag to re-enable it, for the rare case where we want to 
> > debug a hard deadlock while running perf stat ...
> 
> I'd probably only need to save the previous state, in case it was
> disabled for whatever reason.
> 
> So actually, I'll make it so that we restore the previous state at exit.
> Whatever it was. But while perf stat runs as root, we will disable it by
> default.
> 
> /me scratches head a bit...
> 
> Oh ok, even better - no need for a cmdline option then.
> 
> Or does it *ever* make sense to have watchdog running *while* perf stat
> runs too?

Yeah, if for some whatever reason perf locks up while running perf stat as root, 
so I'd keep the option, as a general principle. :-/

Thanks,

	Ingo