[PATCH 3/4] sched/fair: Do not replace recent_used_cpu with the new target

[Hillf Danton]

On Fri, 11 Dec 2020 09:02:28 +0000 Mel Gorman wrote:
>On Fri, Dec 11, 2020 at 02:25:42PM +0800, Hillf Danton wrote:
>> On Tue,  8 Dec 2020 15:35:00 +0000 Mel Gorman wrote:
>> > @@ -6277,17 +6277,13 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
>> >  
>> >  	/* Check a recently used CPU as a potential idle candidate: */
>> >  	recent_used_cpu = p->recent_used_cpu;
>> > +	p->recent_used_cpu = prev;
>> >  	if (recent_used_cpu != prev &&
>> >  	    recent_used_cpu != target &&
>> >  	    cpus_share_cache(recent_used_cpu, target) &&
>> >  	    (available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) &&
>> >  	    cpumask_test_cpu(p->recent_used_cpu, p->cpus_ptr) &&
>> 
>> Typo? Fix it in spin if so.
>> 
>
>What typo?

After your change it is prev that we check against p->cpus_ptr instead of
the recent CPU. Wonder the point to do such a check for returning the
recent one.