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cpumask: Simplify sched_rt.c

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find_lowest_rq() wants to call pick_optimal_cpu() on the
intersection of sched_domain_span(sd) and lowest_mask.  Rather
than doing a cpus_and into a temporary, we can open-code it.

This actually makes the code slightly clearer, IMHO.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Gregory Haskins <ghaskins@novell.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <200911031453.15350.rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Rusty Russell 2009-11-03 14:53:15 +10:30 committed by Ingo Molnar
parent 45a5c8bad8
commit e2c8806304
1 changed files with 23 additions and 36 deletions
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51
kernel/sched_rt.c
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@ -1153,29 +1153,12 @@ static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
static inline int pick_optimal_cpu(int this_cpu,
const struct cpumask *mask)
{
int first;
/* "this_cpu" is cheaper to preempt than a remote processor */
if ((this_cpu != -1) && cpumask_test_cpu(this_cpu, mask))
return this_cpu;
first = cpumask_first(mask);
if (first < nr_cpu_ids)
return first;
return -1;
}
static int find_lowest_rq(struct task_struct *task)
{
struct sched_domain *sd;
struct cpumask *lowest_mask = __get_cpu_var(local_cpu_mask);
int this_cpu = smp_processor_id();
int cpu = task_cpu(task);
cpumask_var_t domain_mask;
if (task->rt.nr_cpus_allowed == 1)
return -1; /* No other targets possible */
@ -1198,36 +1181,40 @@ static int find_lowest_rq(struct task_struct *task)
* Otherwise, we consult the sched_domains span maps to figure
* out which cpu is logically closest to our hot cache data.
*/
if (this_cpu == cpu)
this_cpu = -1; /* Skip this_cpu opt if the same */
if (!cpumask_test_cpu(this_cpu, lowest_mask))
this_cpu = -1; /* Skip this_cpu opt if not among lowest */
if (alloc_cpumask_var(&domain_mask, GFP_ATOMIC)) {
for_each_domain(cpu, sd) {
if (sd->flags & SD_WAKE_AFFINE) {
int best_cpu;
cpumask_and(domain_mask,
sched_domain_span(sd),
lowest_mask);
/*
* "this_cpu" is cheaper to preempt than a
* remote processor.
*/
if (this_cpu != -1 &&
cpumask_test_cpu(this_cpu, sched_domain_span(sd)))
return this_cpu;
best_cpu = pick_optimal_cpu(this_cpu,
domain_mask);
if (best_cpu != -1) {
free_cpumask_var(domain_mask);
best_cpu = cpumask_first_and(lowest_mask,
sched_domain_span(sd));
if (best_cpu < nr_cpu_ids)
return best_cpu;
}
}
}
free_cpumask_var(domain_mask);
}
/*
* And finally, if there were no matches within the domains
* just give the caller *something* to work with from the compatible
* locations.
*/
return pick_optimal_cpu(this_cpu, lowest_mask);
if (this_cpu != -1)
return this_cpu;
cpu = cpumask_any(lowest_mask);
if (cpu < nr_cpu_ids)
return cpu;
return -1;
}
/* Will lock the rq it finds */