If there are idle pcpus inside the waking vcpu's
soft-affinity mask, we should really tickle one
of them (this is one of the purposes of the
__runq_tickle() function itself!), not just
any idle pcpu.
The issue has been introduced in 02ea5031825d
("credit1: properly deal with pCPUs not in any cpupool"),
where the usage of idle_mask is changed, without
updating the bottom of the function, where it
is also referenced.
Signed-off-by: Dario Faggioli <dario.faggi...@citrix.com>
---
Cc: George Dunlap <george.dun...@citrix.eu.com>
Cc: Anshul Makkar <anshul.mak...@citrix.com>
Cc: David Vrabel <david.vra...@citrix.com>
---
David, a while ago you asked what could have been that was causing awful
results for Credit1, for CPU bound workloads, in the overloaded scenario of one
of my benchmarks. I think the bug fixed either here or in next patch (but I'd
be rather sure it's this one) is where the problem was. :-)
---
xen/common/sched_credit.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c
index 6eccf09..3d4f223 100644
--- a/xen/common/sched_credit.c
+++ b/xen/common/sched_credit.c
@@ -454,11 +454,12 @@ static inline void __runq_tickle(struct csched_vcpu *new)
if ( opt_tickle_one_idle )
{
this_cpu(last_tickle_cpu) =
- cpumask_cycle(this_cpu(last_tickle_cpu), &idle_mask);
+ cpumask_cycle(this_cpu(last_tickle_cpu),
+ cpumask_scratch_cpu(cpu));
__cpumask_set_cpu(this_cpu(last_tickle_cpu), &mask);
}
else
- cpumask_or(&mask, &mask, &idle_mask);
+ cpumask_or(&mask, &mask, cpumask_scratch_cpu(cpu));
}
/* Did we find anyone? */
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