[Intel-gfx] [PATCH i-g-t v4] lib/igt_core: Prefer CLOCK_MONOTONIC_RAW

[Chris Wilson]

On Thu, Nov 19, 2015 at 01:00:07PM +0200, Joonas Lahtinen wrote:
> CLOCK_MONOTONIC_RAW is not affected by NTP, so it should be THE clock
> used for timing execution of tests.
> 
> When fetching either the starting or ending time of a test, show the
> time as -1.000s.
> 
> v4:
> - Introduce time_valid macro (Chris)
> - Reduce amount of boilerplate code for calculating elapsed time
> 
> v3:
> - Do not exit directly from handler (Chris)
> - Show elapsed time as -1 if it is not calculable
> 
> v2:
> - Cache the used clock (Chris)
> - Do not change the clock during execution
> - Spit out and error if monotonic time can not be read
> 
> Cc: Thomas Wood <thomas.wood at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

> +static int gettime(struct timespec *ts)
>  {
>  	memset(ts, 0, sizeof(*ts));
> +	errno = 0;
>  
> +	// Stay on the same clock for consistency.

We avoid using "//" for comments, even for single lines.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre