xen: credit2: respect credit2_runqueue=all when arranging runqueues

Commit Message

Marek Marczykowski-Górecki Sept. 19, 2022, 3:04 p.m. UTC

Documentation for credit2_runqueue=all says it should create one queue
for all pCPUs on the host. But since introduction
sched_credit2_max_cpus_runqueue, it actually created separate runqueue
per socket, even if the CPUs count is below
sched_credit2_max_cpus_runqueue.

Adjust the condition to skip syblink check in case of
credit2_runqueue=all.

Fixes: 8e2aa76dc167 ("xen: credit2: limit the max number of CPUs in a runqueue")
Signed-off-by: Marek Marczykowski-Górecki <[e-mail]>
---
The whole thing is under cpu_runqueue_match() already, so maybe
cpu_runqueue_siblings_match() isn't needed at all?
---
 xen/common/sched/credit2.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Patch

diff --git a/xen/common/sched/credit2.c b/xen/common/sched/credit2.c
index 0e3f89e5378e..9b8ca4d5ae24 100644
--- a/xen/common/sched/credit2.c
+++ b/xen/common/sched/credit2.c
@@ -996,9 +996,13 @@  cpu_add_to_runqueue(const struct scheduler *ops, unsigned int cpu)
              *
              * Otherwise, let's try to make sure that siblings stay in the
              * same runqueue, pretty much under any cinrcumnstances.
+             *
+             * Furthermore, try to respect credit2_runqueue=all, as long as
+             * max_cpus_runq isn't violated.
              */
             if ( rqd->refcnt < max_cpus_runq && (ops->cpupool->gran != SCHED_GRAN_cpu ||
-                  cpu_runqueue_siblings_match(rqd, cpu, max_cpus_runq)) )
+                  cpu_runqueue_siblings_match(rqd, cpu, max_cpus_runq) ||
+                  opt_runqueue == OPT_RUNQUEUE_ALL) )
             {
                 /*
                  * This runqueue is ok, but as we said, we also want an even