Re: [PATCH 11/16] time: optimize tick_check_preferred()

Yury Norov
2022-08-08T16:41:11Z

On Mon, Aug 08, 2022 at 01:42:54PM +0200, Thomas Gleixner wrote:
> On Sat, Aug 06 2022 at 10:30, Thomas Gleixner wrote:
> > On Mon, Jul 18 2022 at 12:28, Yury Norov wrote:
> >
> >> tick_check_preferred() calls cpumask_equal() even if
> >> curdev->cpumask == newdev->cpumask. Fix it.
> >
> > What's to fix here? It's a pointless operation in a slow path and all
> > your "fix' is doing is to make the code larger.

Pointless operation in a slow path is still pointless.

> In fact cpumask_equal() should have the ptr1 == ptr2 check, so you don't
> have to add it all over the place.

This adds to the image size:
add/remove: 1/1 grow/shrink: 24/3 up/down: 507/-46 (461)

The more important, cpumask shouldn't check parameters because this is
an internal function. This whole series point is about adding such checks
under DEBUG_BITMAP config, and not affecting general case.

What about adding cpumask_equal__addr? (Any better name is welcome.)

Thanks,
Yury