Re: [PATCH 0/4] sched: Various reweight_entity() fixes

[Peter Zijlstra]

On Tue, Feb 10, 2026 at 10:46:28AM +0530, K Prateek Nayak wrote:
> Hello Peter,
> 
> On 2/9/2026 9:17 PM, Peter Zijlstra wrote:
> > I ended up with the below; and I've already pushed out a fresh
> > queue/sched/core. Could you please test again?
> 
> I haven't seen any "sum_shifts" turning non-zero on the overnight runs,
> even with the larger workloads, so feel free to include:
> 
> Tested-by: K Prateek Nayak <kprateek.nayak@xxxxxxx>

Awesome, thanks!

> 
> The overall patch looks good. I only have couple of cosmetic nits
> inlined below:
> 
> [..snip..]
> 
> >  u64 avg_vruntime(struct cfs_rq *cfs_rq)
> >  {
> >  	struct sched_entity *curr = cfs_rq->curr;
> > -	s64 avg = cfs_rq->sum_w_vruntime;
> > -	long load = cfs_rq->sum_weight;
> > +	s64 delta = 0, runtime = cfs_rq->sum_w_vruntime;
> 
> nit.
> 
> "runtime" is only ever used in "weight" != 0 case so perhaps it can be
> moved there to preserve the reverse x-mas (or this whole line can be
> moved up top).

Indeed!

> > +	long weight = cfs_rq->sum_weight;
> >  
> > -	if (curr && curr->on_rq) {
> > -		unsigned long weight = scale_load_down(curr->load.weight);
> > +	if (curr && !curr->on_rq)
> > +		curr = NULL;
> >  
> > -		avg += entity_key(cfs_rq, curr) * weight;
> > -		load += weight;
> > -	}
> > +	if (weight) {
> > +		if (curr) {
> > +			unsigned long w = scale_load_down(curr->load.weight);
> > +
> > +			runtime += entity_key(cfs_rq, curr) * w;
> > +			weight += w;
> > +		}
> >  
> > -	if (load) {
> >  		/* sign flips effective floor / ceiling */
> > -		if (avg < 0)
> > -			avg -= (load - 1);
> > -		avg = div_s64(avg, load);
> > +		if (runtime < 0)
> > +			runtime -= (weight - 1);
> > +
> > +		delta = div_s64(runtime, weight);
> > +
> 
> nit. Is this empty line necessary?

Not really, but somehow I always find myself ending a block with an
empty line when there's an else statement following.

I'll get rid of it :-)