[U-Boot] [PATCH] lib: time: Add microsecond timer

[Eugeniu Rosca]

On Wed, Oct 16, 2019 at 07:26:44PM +0200, Marek Vasut wrote:
> On 10/16/19 7:11 PM, Eugeniu Rosca wrote:
> > On Tue, Oct 15, 2019 at 10:43:41PM +0200, Marek Vasut wrote:
> >> Add get_timer_us(), which is useful e.g. when we need higher
> >> precision timestamps.
> > 
> > FWIW, I agree with Simon that bootstage [1] can be an awesome tool for
> > profiling and boot time measurements. With a bit of instrumentation and
> > host-side scripting, it allows to produce accurate bootcharts like [2].
> > 
> > [1] https://patchwork.ozlabs.org/patch/1177393/#2281091
> > [2] https://i.ibb.co/mG6Xc1p/2019-10-16-190251.png
> 
> I don't need that though, I really only need to know how long the code
> spent between two points in code.

It can be accomplished in N ways. A quick and dirty way to use
"bootstage" would be to add below instrumentation:

 ----------8<----------
bootstage_mark_name(BOOTSTAGE_ID_ALLOC, "count/time from here");
/*
 * my-precious-code
 */
bootstage_mark_name(BOOTSTAGE_ID_ALLOC, "duration of my-precious-code");
 ----------8<----------

It's likely orthogonal to what's being proposed in your patch.

-- 
Best Regards,
Eugeniu