On 5/12/2017 2:47 PM, Peter Zijlstra wrote:
On Fri, May 12, 2017 at 11:01:37AM -0600, Jeffrey Hugo wrote:
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d711093..8f783ba 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8219,8 +8219,19 @@ static int load_balance(int this_cpu, struct rq *this_rq,
/* All tasks on this runqueue were pinned by CPU affinity */
if (unlikely(env.flags & LBF_ALL_PINNED)) {
+ struct cpumask tmp;
You cannot have cpumask's on stack.
Well, we need a temp variable to store the intermediate values since the
cpumask_* operations are somewhat limited, and require a "storage"
parameter.
Do you have any suggestions to meet all of these requirements?
+
+ /* Cpumask of all initially possible busiest cpus. */
+ cpumask_copy(&tmp, sched_domain_span(env.sd));
+ cpumask_clear_cpu(env.dst_cpu, &tmp);
You forgot to mask with cpu_active_mask.
cpus == cpu_active_mask, which we compare against below in just a few
lines with the cpumask_intersects check. So, no, I don't think we did
forget to mask with cpu_active_mask.
+
cpumask_clear_cpu(cpu_of(busiest), cpus);
- if (!cpumask_empty(cpus)) {
+ /*
+ * Go back to "redo" iff the load-balance cpumask
+ * contains other potential busiest cpus for the
+ * current sched domain.
+ */
+ if (cpumask_intersects(cpus, &tmp)) {
env.loop = 0;
env.loop_break = sched_nr_migrate_break;
goto redo;
--
Jeffrey Hugo
Qualcomm Datacenter Technologies as an affiliate of Qualcomm
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
