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

[Eugeniu Rosca]

On Wed, Oct 16, 2019 at 07:43:09PM +0200, Eugeniu Rosca wrote:
> 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.

Bottom line is "bootstage" already makes use of timer_get_boot_us(), so
it's not entirely clear to me why another us-resolution timer API would
be needed.

-- 
Best Regards,
Eugeniu