Re: [PATCH v4 12/17] s390/preempt: Enable HAS_SEPARATE_PREEMPT_RESCHED_BITS

[Peter Zijlstra]

On Wed, Aug 05, 2026 at 01:57:04AM +0530, Shrikanth Hegde wrote:
> +maddy, christophe,
> 
> On 8/4/26 9:44 PM, Boqun Feng wrote:
> > From: Heiko Carstens <hca@xxxxxxxxxxxxx>
> > 
> > Convert s390's preempt_count to 64 bit, and change the preempt
> > primitives accordingly.
> > 
> 
> > +	union {
> > +		struct {
> > +			__u32	need_resched;	/* 0x03a8 */
> > +			__u32	count;		/* 0x03ac */
> > +		} preempt;
> > +		__u64	preempt_count;		/* 0x03a8 */
> > +	};
> 
> 
> This is interesting. So arm64, s390 will have similar implementation
> w.r.t to preempt_count.
> 
> I guess PoC that i was trying for ppc64 is worth pursuing even more,
> since ppc64 is one missing major arch which still uses old method
> of querying tif_need_resched.
> With similar change ppc64 can set HAS_SEPARATE_PREEMPT_RESCHED_BITS too.

Yes. PPC should be able to the same thing ARM64 does.