On Wed, Jul 31, 2019 at 11:03:01AM -0400, Rik van Riel wrote:
> I think I understand the problem you are pointing out, but if
> update_load_avg() keeps the load average for the runqueue unchanged
> (because that is rate limited to once a jiffy, and has been like that
> for a while), why would calc_group_shares() result in a different
> value than what it returned the last time?
>
> What am I overlooking?
I'm thinking you're thinking (3):
tg->weight * grq->avg.load_avg
shares = ------------------------------
tg->load_avg
Where: tg->load_avg ~= \Sum grq->avg.load_avg
Which is the straight forward shares calculation, and purely depends on
the load averages (which haven't been changed etc..)
But what we actually do is (6):
tg->weight * grq->avg.load_avg
shares =
---------------------------------------------------------------------------
tg->load_avg - grq->avg.load_avg + max(grq->load.weight,
grq->avg.load_avg)
And even if tg->load_avg and grq->avg.load_avg haven't changed,
grq->load.weight most certainly has.
