linux-kernel - Re: [PATCH] trace: Default to using trace_global_clock if sched

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Message-ID: <20180330103738.7f8a959b@gandalf.local.home>
Date:   Fri, 30 Mar 2018 10:37:38 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Chris Wilson <chris@...is-wilson.co.uk>
Cc:     linux-kernel@...r.kernel.org, intel-gfx@...ts.freedesktop.org
Subject: Re: [PATCH] trace: Default to using trace_global_clock if
 sched_clock is unstable

On Fri, 30 Mar 2018 15:07:53 +0100
Chris Wilson <chris@...is-wilson.co.uk> wrote:

> Sure, I was mainly floating the idea of trying to pick sensible
> defaults. Unstable clocks are quite rare nowadays, the ones we have in
> the lab are a pair of Core2 Duo.

I still have a box too ;-)

I'm not so against having global_clock become default if the TSC is
unstable. But there needs to be a printk warning (not a WARN, but
something like: 

 Warning: TSC unstable, switching tracing_clock default to "global"
 If you want to keep local, then add "trace_clock=local" on the
  kernel command line.

-- Steve