[ovs-dev,v3,2/4] dpif-netdev: Avoid reading RSS hash when EMC is disabled

Submitted by Fischetti, Antonio on Aug. 11, 2017, 3:52 p.m.

Details

Message ID 1502466766-17370-3-git-send-email-antonio.fischetti@intel.com
State New
Headers show

Commit Message

Fischetti, Antonio Aug. 11, 2017, 3:52 p.m.
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 <antonio.fischetti@intel.com>
---
This patch depends on previous patch in this series.

Port-to-Port Test

Comments

Darrell Ball Aug. 14, 2017, 6:32 a.m.
I did not try it yet, but seems reasonable
If the hash is needed for something else, it will be read at that point. 

-----Original Message-----
From: <ovs-dev-bounces@openvswitch.org> on behalf of "antonio.fischetti@intel.com" <antonio.fischetti@intel.com>
Date: Friday, August 11, 2017 at 8:52 AM
To: "dev@openvswitch.org" <dev@openvswitch.org>
Subject: [ovs-dev] [PATCH v3 2/4] dpif-netdev: Avoid reading RSS hash when	EMC is disabled

    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 <antonio.fischetti@intel.com>
    ---
    This patch depends on previous patch in this series.
    
    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.
    
    EMC column:
       Yes: default probability insertion,
       No: EMC disabled.
    
    Orig OvS-DPDK means Commit ID:
      6b1babacc3ca0488e07596bf822fe356c9bab646
    
                +--------------+----------------+----------------+
    +-----+-----+    Orig      | Orig + patch 1 | Orig + patch 1 |
    | RSS | EMC |              |                |  this patch    |
    +-----+-----+--------------+----------------+----------------+
    | Yes | Yes | 11.99, 11.41 | 12.20, 11.31   | 12.20, 11.31   |
    | Yes |  No |  8.32,  8.42 |  8.35,  8.39   |  8.62, 8.62    |
    +-----+-----+--------------+----------------+----------------+
    |  No | Yes |  9.87, 11.15 |  9.79, 11.20   |  9.85, 11.09   |
    |  No |  No |  7.82,  7.84 |  7.84,  7.93   |  8.40,  8.38   |
    +-----+-----+--------------+----------------+----------------+
    ---
     lib/dpif-netdev.c | 20 +++++++++++++++++++-
     1 file changed, 19 insertions(+), 1 deletion(-)
    
    diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
    index 8f6b96b..0db6f83 100644
    --- a/lib/dpif-netdev.c
    +++ b/lib/dpif-netdev.c
    @@ -4578,6 +4578,22 @@ 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)
     {
    @@ -4715,7 +4731,6 @@ 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);
     
             /*
              * EMC lookup is skipped when one or both of the following
    @@ -4732,9 +4747,12 @@ emc_processing(struct dp_netdev_pmd_thread *pmd,
              */
             if (OVS_LIKELY(cur_min)) {
                 if (!md_is_valid) {
    +                key->hash = dpif_netdev_packet_get_rss_hash_orig_pkt(packet,
    +                        &key->mf);
                     flow = emc_lookup(flow_cache, key);
                 } else {
                     /* Recirculated packet. */
    +                key->hash = dpif_netdev_packet_get_rss_hash(packet, &key->mf);
                     if (flow_cache->n_entries & EMC_RECIRCT_NO_INSERT_THRESHOLD) {
                         /* EMC occupancy is over the threshold.  We skip EMC
                          * lookup for recirculated packets. */
    -- 
    2.4.11
    
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=================
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.

EMC column:
   Yes: default probability insertion,
   No: EMC disabled.

Orig OvS-DPDK means Commit ID:
  6b1babacc3ca0488e07596bf822fe356c9bab646

            +--------------+----------------+----------------+
+-----+-----+    Orig      | Orig + patch 1 | Orig + patch 1 |
| RSS | EMC |              |                |  this patch    |
+-----+-----+--------------+----------------+----------------+
| Yes | Yes | 11.99, 11.41 | 12.20, 11.31   | 12.20, 11.31   |
| Yes |  No |  8.32,  8.42 |  8.35,  8.39   |  8.62, 8.62    |
+-----+-----+--------------+----------------+----------------+
|  No | Yes |  9.87, 11.15 |  9.79, 11.20   |  9.85, 11.09   |
|  No |  No |  7.82,  7.84 |  7.84,  7.93   |  8.40,  8.38   |
+-----+-----+--------------+----------------+----------------+
---
 lib/dpif-netdev.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index 8f6b96b..0db6f83 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -4578,6 +4578,22 @@  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)
 {
@@ -4715,7 +4731,6 @@  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);
 
         /*
          * EMC lookup is skipped when one or both of the following
@@ -4732,9 +4747,12 @@  emc_processing(struct dp_netdev_pmd_thread *pmd,
          */
         if (OVS_LIKELY(cur_min)) {
             if (!md_is_valid) {
+                key->hash = dpif_netdev_packet_get_rss_hash_orig_pkt(packet,
+                        &key->mf);
                 flow = emc_lookup(flow_cache, key);
             } else {
                 /* Recirculated packet. */
+                key->hash = dpif_netdev_packet_get_rss_hash(packet, &key->mf);
                 if (flow_cache->n_entries & EMC_RECIRCT_NO_INSERT_THRESHOLD) {
                     /* EMC occupancy is over the threshold.  We skip EMC
                      * lookup for recirculated packets. */