Re: [PATCH v3 2/2] rust: use Delta and a Jiffies newtype for timeouts and delays

On Mon, Jul 20, 2026 at 2:48 AM FUJITA Tomonori <[email protected]> wrote:
> On Sat, 18 Jul 2026 16:20:10 +0100
> "Gary Guo" <[email protected]> wrote:
> > I wonder if we should have time types being generic over units. So you can have
> > `Delta<Nsec>` and `Delta<Jiffy>` and `Instant<Nsec>`, `Instant<Jiffy>`, with the
> > generic default being set to `Nsec`.
> >
> >     Delta::new(42) // Delta<Nsec>
> >     Delta::new_jiffies(42) // Delta<Jiffy>
> >
> > Thoughts?
>
> I think making Delta generic over the time unit makes sense; Delta
> <Nsec> and Delta<Jiffy>.
>
> However, I don't think making Instant generic over the time unit is a
> good idea, even though it clearly is for Delta.
>
> Instant is already generic over ClockSource, and jiffies is not a
> clock source: it has no clockid_t, it is read via get_jiffies_64()
> rather than ktime_get(), and it cannot be armed through hrtimer. That
> leaves two ways to force a jiffies Instant, both looks wrong:

I read the above and thought, "but jiffies is a clocksource":
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/time/jiffies.c#n21

And then I realized there has been some unfortunate naming overlap,
where it seems the rust ClockSource seems to map to the clockid_t, not
to the clocksource concept that Linux uses to abstract the hardware
counter used as a source of time (for the majority of the clockids).

Very much a bikeshed request, but is it too late to rename this to
ClockID or something? So there is maybe less confusion when reading
across C and Rust code?

thanks
-john