On 07/04/2013 05:13 PM, Peter Zijlstra wrote:
[snip]
>
> Right, but something like the below is limited in cost to at most 32/64 (I
> forgot the type) shifts. Now its probably not worth doing, but it shows
> things like that can be done in 'constant' time.
>
> now = jiffies;
> if (now - p->last_switch_decay > 8*sizeof(p->nr_wakee_switch)*HZ) {
> p->nr_wakee_switch = 0;
> p->last_switch_decay = now;
> } else while (now > p->last_switch_decay + HZ) {
> p->nr_wakee_switch >>= 1;
> p->last_switch_decay += HZ;
> }
Hmm...interesting, some kind of cataclysm decay, not sure how it works
but yes, the cost was capped.
Well, seems like we still have many follow-up research works after fix
the issue ;-)
Regards,
Michael Wang
>
>
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