On Wed, 2007-07-11 at 04:42 -0700, Paul Jackson wrote:
> Srivatsa wrote:
> > The fact that we will have two interface for group scheduler in 2.6.24
> > is what worries me a bit (one user-id based and other container based).
>
> Yeah.
>
> One -could- take linear combinations, as Peter drew in his ascii art,
> but would one -want- to do that?
I'd very much like to have it, but that is just me. We could take a
weight of 0 to mean disabling of that grouping and default to that. That
way it would not complicate regular behaviour.
It could be implemented with a simple hashing scheme where
sched_group_hash(tsk) and sched_group_cmp(tsk, group->some_task) could
be used to identify a schedule group.
pseudo code:
u64 sched_group_hash(struct task_struct *tsk)
{
u64 hash = 0;
if (tsk->pid->weight)
hash_add(&hash, tsk->pid);
if (tsk->pgrp->weight)
hash_add(&hash, tsk->pgrp);
if (tsk->uid->weight)
hash_add(&hash, tsk->uid);
if (tsk->container->weight)
hash_add(&hash, tsk->container);
...
return hash;
}
s64 sched_group_cmp(struct task_struct *t1, struct task_struct *t2)
{
s64 cmp;
if (t1->pid->weight || t2->pid->weight) {
cmp = t1->pid->weight - t2->pid->weight;
if (cmp)
return cmp;
}
...
return 0;
}
u64 sched_group_weight(struct task_struct *tsk)
{
u64 weight = 1024; /* 1 fixed point 10 bits */
if (tsk->pid->weight) {
weight *= tsk->pid->weight;
weight /= 1024;
}
....
return weight;
}
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