Re: sched_clock and device suspend/resume

[Thomas Gleixner]

On Wed, 10 Jul 2019, Steven Rostedt wrote:

> 
> [ Resending as your Cc was screwed up and caused my reply to mess up
>   the Cc list ]
> 
> On Wed, 10 Jul 2019 08:20:37 -0700
> Sodagudi Prasad <psodagud@xxxxxxxxxxxxxx> wrote:
> 
> > Another option is printing the epoch/cycles information in every print 
> > statement similar to thread id or processor id added 
> > recently(CONFIG_PRINTK_CALLER). This can be avoided if we start 
> > accounting suspend time in sched_clock.
> 
> Or another option is add a new clock that printk and tracing can use.
> tracing already can switch between clocks trivially.
> 
> sched_clock_continuous() ? (I know, horrible name), that simply keeps
> track of the time delta at suspend and returns:
> 
> 	sched_clock() + delta;

Which you get already when you do

# echo boot > /sys/kernel/debug/tracing/trace_clock

Thanks,

	tglx