Hi Antonio
On 8/25/17, 6:56 AM, "[email protected] on behalf of
[email protected]" <[email protected] on behalf of
[email protected]> wrote:
When EMC is disabled the reading of RSS hash is skipped.
Also, for packets that are not recirculated it retrieves
the hash value without considering the recirc id.
Signed-off-by: Antonio Fischetti <[email protected]>
---
V4
- reworked to remove dependencies from other patches in
patchset "Skip EMC for recirc pkts and other optimizations."
https://urldefense.proofpoint.com/v2/url?u=https-3A__mail.openvswitch.org_pipermail_ovs-2Ddev_2017-2DAugust_337320.html&d=DwICAg&c=uilaK90D4TOVoH58JNXRgQ&r=BVhFA09CGX7JQ5Ih-uZnsw&m=7UGZunJeutRugFmidRAykhZFRYscZ2rUUmhF7Ys9IM8&s=hzVGT1bI3zOj_x9J5cu18Q2D5WLHdEC1qhQ-Gu--TEE&e=
- measurements were repeated with the latest head of master.
Port-to-Port Test
=================
Software built with "-O2 -march=native -g".
I measured the Rx rate regardless of pkt loss by sending 1 UDP flow,
64B packets, at the line-rate.
2 PMDs with 3 Tx queues.
Flows setup:
in_port=dpdk0 actions=output:dpdk1
in_port=dpdk1 actions=output:dpdk0
Results
-------
Values are for the Rx rate in Mpps, regardless of packet loss.
RSS column:
Yes: RSS hash is provided by the NIC
No: RSS is disabled and the 5-tuple hash must be
computed in software.
Note: to simulate RSS disabled I added the line
dp_packet_rss_valid(struct dp_packet *p)
{
+return false;
#ifdef DPDK_NETDEV
EMC column:
Yes: default probability insertion,
No: EMC disabled.
Orig means Commit ID:
75f9e007e7f7eb91461e238f882d1c539c56bb8d
[Darrell]
It looks like the main benefit (+6% throughput) occurs
when RSS is not calculated by the NIC and emc is disabled. What are the common
cases when RSS is not generated by the NIC ?
+--------------+----------------+
+-----+-----+ Orig | Orig + this |
| RSS | EMC | | patch |
+-----+-----+--------------+----------------+
| Yes | Yes | 12.02, 11.38 | 12.18, 11.32 |
| Yes | No | 8.35, 8.36 | 8.36, 8.38 |
+-----+-----+--------------+----------------+
| No | Yes | 9.91, 11.15 | 9.84, 11.08 |
| No | No | 7.83, 7.87 | 8.33, 8.35 |
+-----+-----+--------------+----------------+
---
lib/dpif-netdev.c | 32 ++++++++++++++++++++++++++++----
1 file changed, 28 insertions(+), 4 deletions(-)
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index e2cd931..1157998 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -4567,6 +4567,22 @@ dp_netdev_upcall(struct dp_netdev_pmd_thread *pmd,
struct dp_packet *packet_,
}
static inline uint32_t
+dpif_netdev_packet_get_rss_hash_orig_pkt(struct dp_packet *packet,
+ const struct miniflow *mf)
+{
+ uint32_t hash;
+
+ if (OVS_LIKELY(dp_packet_rss_valid(packet))) {
+ hash = dp_packet_get_rss_hash(packet);
+ } else {
+ hash = miniflow_hash_5tuple(mf, 0);
+ dp_packet_set_rss_hash(packet, hash);
+ }
+
+ return hash;
+}
+
+static inline uint32_t
dpif_netdev_packet_get_rss_hash(struct dp_packet *packet,
const struct miniflow *mf)
{
@@ -4701,10 +4717,18 @@ emc_processing(struct dp_netdev_pmd_thread *pmd,
}
miniflow_extract(packet, &key->mf);
key->len = 0; /* Not computed yet. */
- key->hash = dpif_netdev_packet_get_rss_hash(packet, &key->mf);
-
- /* If EMC is disabled skip emc_lookup */
- flow = (cur_min == 0) ? NULL: emc_lookup(flow_cache, key);
+ /* If EMC is disabled skip hash computation and emc_lookup */
+ if (OVS_LIKELY(cur_min)) {
+ if (!md_is_valid) {
+ key->hash =
dpif_netdev_packet_get_rss_hash_orig_pkt(packet,
+ &key->mf);
+ } else {
+ key->hash = dpif_netdev_packet_get_rss_hash(packet,
&key->mf);
+ }
+ flow = emc_lookup(flow_cache, key);
+ } else {
+ flow = NULL;
+ }
if (OVS_LIKELY(flow)) {
dp_netdev_queue_batches(packet, flow, &key->mf, batches,
n_batches);
--
2.4.11
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