[ovs-dev] [PATCH] dpif-netdev: Allow PMD auto load balance with cross-numa.

Kevin Traynor ktraynor at redhat.com
Thu Mar 11 15:04:39 UTC 2021


Previously auto load balance did not trigger a reassignment when
there was any cross-numa polling as an rxq could be polled from a
different numa after reassign and it could impact estimates.

In the case where there is only one numa with pmds available, the
same numa will always poll before and after reassignment, so estimates
are valid. Allow PMD auto load balance to trigger a reassignment in
this case.

Signed-off-by: Kevin Traynor <ktraynor at redhat.com>
---
 lib/dpif-netdev.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index 816945375..19a6ac2d9 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -4888,4 +4888,10 @@ struct rr_numa {
 };
 
+static size_t
+rr_numa_list_count(struct rr_numa_list *rr)
+{
+    return hmap_count(&rr->numas);
+}
+
 static struct rr_numa *
 rr_numa_list_lookup(struct rr_numa_list *rr, int numa_id)
@@ -5601,8 +5607,14 @@ get_dry_run_variance(struct dp_netdev *dp, uint32_t *core_list,
         numa = rr_numa_list_lookup(&rr, numa_id);
         if (!numa) {
-            /* Abort if cross NUMA polling. */
-            VLOG_DBG("PMD auto lb dry run."
-                     " Aborting due to cross-numa polling.");
-            goto cleanup;
+            /* Check if there is just one NUMA with pmds,
+             * in that case estimates will be valid. */
+            if (rr_numa_list_count(&rr) == 1) {
+                numa = rr_numa_list_next(&rr, NULL);
+            }
+            if (!numa) {
+                VLOG_DBG("PMD auto lb dry run."
+                        " Aborting due to cross-numa polling.");
+                goto cleanup;
+            }
         }
 
-- 
2.29.2



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