[POWERPC] spu sched: forced preemption at execution
If we start a spu context with realtime priority we want it to run immediately and not wait until some other lower priority thread has finished. Try to find a suitable victim and use it's spu in this case. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
This commit is contained in:
parent
ae7b4c5284
commit
52f04fcf66
|
@ -53,6 +53,7 @@ struct spu_context *alloc_spu_context(struct spu_gang *gang)
|
|||
ctx->owner = get_task_mm(current);
|
||||
if (gang)
|
||||
spu_gang_add_ctx(gang, ctx);
|
||||
ctx->rt_priority = current->rt_priority;
|
||||
ctx->prio = current->prio;
|
||||
goto out;
|
||||
out_free:
|
||||
|
|
|
@ -281,6 +281,74 @@ static struct spu *spu_get_idle(struct spu_context *ctx)
|
|||
return spu;
|
||||
}
|
||||
|
||||
/**
|
||||
* find_victim - find a lower priority context to preempt
|
||||
* @ctx: canidate context for running
|
||||
*
|
||||
* Returns the freed physical spu to run the new context on.
|
||||
*/
|
||||
static struct spu *find_victim(struct spu_context *ctx)
|
||||
{
|
||||
struct spu_context *victim = NULL;
|
||||
struct spu *spu;
|
||||
int node, n;
|
||||
|
||||
/*
|
||||
* Look for a possible preemption candidate on the local node first.
|
||||
* If there is no candidate look at the other nodes. This isn't
|
||||
* exactly fair, but so far the whole spu schedule tries to keep
|
||||
* a strong node affinity. We might want to fine-tune this in
|
||||
* the future.
|
||||
*/
|
||||
restart:
|
||||
node = cpu_to_node(raw_smp_processor_id());
|
||||
for (n = 0; n < MAX_NUMNODES; n++, node++) {
|
||||
node = (node < MAX_NUMNODES) ? node : 0;
|
||||
if (!node_allowed(node))
|
||||
continue;
|
||||
|
||||
mutex_lock(&spu_prio->active_mutex[node]);
|
||||
list_for_each_entry(spu, &spu_prio->active_list[node], list) {
|
||||
struct spu_context *tmp = spu->ctx;
|
||||
|
||||
if (tmp->rt_priority < ctx->rt_priority &&
|
||||
(!victim || tmp->rt_priority < victim->rt_priority))
|
||||
victim = spu->ctx;
|
||||
}
|
||||
mutex_unlock(&spu_prio->active_mutex[node]);
|
||||
|
||||
if (victim) {
|
||||
/*
|
||||
* This nests ctx->state_mutex, but we always lock
|
||||
* higher priority contexts before lower priority
|
||||
* ones, so this is safe until we introduce
|
||||
* priority inheritance schemes.
|
||||
*/
|
||||
if (!mutex_trylock(&victim->state_mutex)) {
|
||||
victim = NULL;
|
||||
goto restart;
|
||||
}
|
||||
|
||||
spu = victim->spu;
|
||||
if (!spu) {
|
||||
/*
|
||||
* This race can happen because we've dropped
|
||||
* the active list mutex. No a problem, just
|
||||
* restart the search.
|
||||
*/
|
||||
mutex_unlock(&victim->state_mutex);
|
||||
victim = NULL;
|
||||
goto restart;
|
||||
}
|
||||
spu_unbind_context(spu, victim);
|
||||
mutex_unlock(&victim->state_mutex);
|
||||
return spu;
|
||||
}
|
||||
}
|
||||
|
||||
return NULL;
|
||||
}
|
||||
|
||||
/**
|
||||
* spu_activate - find a free spu for a context and execute it
|
||||
* @ctx: spu context to schedule
|
||||
|
@ -300,6 +368,12 @@ int spu_activate(struct spu_context *ctx, unsigned long flags)
|
|||
struct spu *spu;
|
||||
|
||||
spu = spu_get_idle(ctx);
|
||||
/*
|
||||
* If this is a realtime thread we try to get it running by
|
||||
* preempting a lower priority thread.
|
||||
*/
|
||||
if (!spu && ctx->rt_priority)
|
||||
spu = find_victim(ctx);
|
||||
if (spu) {
|
||||
spu_bind_context(spu, ctx);
|
||||
return 0;
|
||||
|
|
|
@ -83,6 +83,7 @@ struct spu_context {
|
|||
/* scheduler fields */
|
||||
struct list_head rq;
|
||||
unsigned long sched_flags;
|
||||
unsigned long rt_priority;
|
||||
int prio;
|
||||
};
|
||||
|
||||
|
|
Loading…
Reference in a new issue