On Mon, 22 May 2017, Arnd Bergmann wrote:

On Sun, May 21, 2017 at 8:14 PM, Thomas Gleixner [off-list ref] wrote:

quoted

But it's easy enough to provide them. All we need for that is something
like

        unsigned long time_msec;

which gets incremented every tick by the appropriate amount of
milliseconds.

Having that would also allow to replace all the

       end = jiffies + msec_to_jiffies(xxx);

       while (time_before(jiffies, end))
             ....

constructs with a milliseconds based machinery. So we can remove all
*_to_jiffies() interfaces over time.

A lot of those users could probably just ktime_get()/ktime_before() here,
as they would by definition not be performance critical.

Right.

I don't see a way to just tk->tkr_mono.base but with a ktime_get_coarse()
we could just return the ktime_t of the last tick and not even need a seqlock
on 64-bit architectures, or have to introduce a new API.

Yeah, that would be possible, but OTOH, for those loop thingies it probably
does not matter at all whether you have the overhead of ktime_get() or
not. We need to look at that stuff deeper.

Thanks,

	tglx