Having the same RSS hash after recirculation can cause unnecessary
collisions in the exact match cache. A simple solution is to rehash it
with the recirculation depth if it is non-zero
Suggested-by: Ethan Jackson <et...@nicira.com>
Signed-off-by: Daniele Di Proietto <diproiet...@vmware.com>
---
v1->v2:
* Dropped the merged commits
* Rename dpif_netdev_packet_get_dp_hash() to
dpif_netdev_packet_get_rss_hash()
---
lib/dpif-netdev.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index f1d65f5..b84cd53 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -3007,16 +3007,24 @@ dp_netdev_upcall(struct dp_netdev_pmd_thread *pmd,
struct dp_packet *packet_,
}
static inline uint32_t
-dpif_netdev_packet_get_dp_hash(struct dp_packet *packet,
- const struct miniflow *mf)
+dpif_netdev_packet_get_rss_hash(struct dp_packet *packet,
+ const struct miniflow *mf)
{
- uint32_t hash;
+ uint32_t hash, recirc_depth;
hash = dp_packet_get_rss_hash(packet);
if (OVS_UNLIKELY(!hash)) {
hash = miniflow_hash_5tuple(mf, 0);
dp_packet_set_rss_hash(packet, hash);
}
+
+ /* The RSS hash must account for the recirculation depth to avoid
+ * collisions in the exact match cache */
+ recirc_depth = *recirc_depth_get_unsafe();
+ if (OVS_UNLIKELY(recirc_depth)) {
+ hash = hash_finish(hash, recirc_depth);
+ dp_packet_set_rss_hash(packet, hash);
+ }
return hash;
}
@@ -3142,7 +3150,7 @@ emc_processing(struct dp_netdev_pmd_thread *pmd, struct
dp_packet **packets,
miniflow_extract(packets[i], &key.mf);
key.len = 0; /* Not computed yet. */
- key.hash = dpif_netdev_packet_get_dp_hash(packets[i], &key.mf);
+ key.hash = dpif_netdev_packet_get_rss_hash(packets[i], &key.mf);
flow = emc_lookup(flow_cache, &key);
if (OVS_UNLIKELY(!dp_netdev_queue_batches(packets[i], flow, &key.mf,
--
2.1.4
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