Re: [PATCH] thermal: add ratelimited thermal and power logging

From: Ross Zwisler
Date: Mon Oct 29 2018 - 09:21:42 EST

On Wed, Oct 24, 2018 at 1:22 AM Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
> On 22-10-18, 14:29, Ross Zwisler wrote:
> > From: Ricky Liang <jcliang@xxxxxxxxxxxx>
> >
> > Add thermal logs in devfreq_cooling and cpu_cooling.
> Why should we add them ?
> > Also add logging to
> > power_allocator when it starts to control power.
> >
> > These changes can lead to excessive log spam when running up against
> > thermal limits, so have this logging ratelimited to allow only 1 log each
> > 30 seconds from each of those subsystems.
> What's the use of these logs when we are going to print them only once every 30
> seconds ?
> I recently extended thermal sysfs support to share more stats.
> commit 8ea229511e06 ("thermal: Add cooling device's statistics in sysfs")
> Will that be helpful in your case ?
> Otherwise we should probably add trace points instead.

Thank you for the review. Basically we use these prints to get a
notification when a system is having thermal issues. It's easy to
look in dmesg and see the prints and know that something temperature
related is going on.

However, I agree that the current solution is a bit hacky, and in
looking at it a bit further we don't even cover all the paths that we
need to. The processor_set_cur_state() function in
drivers/acpi/processor_thermal.c, for example, is used on the x86_64
systems I'm testing with and wasn't augmented with prints.

I'm going to take a step back and try and find another solution. The
info you added to sysfs looks very promising, thank you for pointing
it out.