INSTALL.DPDK: Update details of XL710 restrictions for DPDK 2.2.

[cascardo/ovs.git] / INSTALL.DPDK.md

diff --git a/INSTALL.DPDK.md b/INSTALL.DPDK.md
index c601358..b0659c9 100644 (file)
--- a/INSTALL.DPDK.md
+++ b/INSTALL.DPDK.md
@@ -294,9 +294,9 @@ Performance Tuning:
 
   3. DPDK port Rx Queues
 
-       `ovs-vsctl set Open_vSwitch . other_config:n-dpdk-rxqs=<integer>`
+       `ovs-vsctl set Interface <DPDK interface> options:n_rxq=<integer>`
 
-       The command above sets the number of rx queues for each DPDK interface.
+       The command above sets the number of rx queues for DPDK interface.
        The rx queues are assigned to pmd threads on the same NUMA node in a
        round-robin fashion.  For more information, please refer to the
        Open_vSwitch TABLE section in
@@ -567,6 +567,25 @@ Follow the steps below to attach vhost-user port(s) to a VM.
    -numa node,memdev=mem -mem-prealloc
    ```
 
+3. Optional: Enable multiqueue support
+   The vhost-user interface must be configured in Open vSwitch with the
+   desired amount of queues with:
+
+   ```
+   ovs-vsctl set Interface vhost-user-2 options:n_rxq=<requested queues>
+   ```
+
+   QEMU needs to be configured as well.
+   The $q below should match the queues requested in OVS (if $q is more,
+   packets will not be received).
+   The $v is the number of vectors, which is '$q x 2 + 2'.
+
+   ```
+   -chardev socket,id=char2,path=/usr/local/var/run/openvswitch/vhost-user-2
+   -netdev type=vhost-user,id=mynet2,chardev=char2,vhostforce,queues=$q
+   -device virtio-net-pci,mac=00:00:00:00:00:02,netdev=mynet2,mq=on,vectors=$v
+   ```
+
 DPDK vhost-cuse:
 ----------------
 
@@ -879,17 +898,17 @@ Restrictions:
     this with smaller page sizes.
 
   Platform and Network Interface:
-  - Currently it is not possible to use an Intel XL710 Network Interface as a
-    DPDK port type on a platform with more than 64 logical cores. This is
-    related to how DPDK reports the number of TX queues that may be used by
-    a DPDK application with an XL710. The maximum number of TX queues supported
-    by a DPDK application for an XL710 is 64. If a user attempts to add an
-    XL710 interface as a DPDK port type to a system as described above the
-    port addition will fail as OVS will attempt to initialize a TX queue greater
-    than 64. This issue is expected to be resolved in a future DPDK release.
-    As a workaround a user can disable hyper-threading to reduce the overall
-    core count of the system to be less than or equal to 64 when using an XL710
-    interface with DPDK.
+  - By default with DPDK 2.2, a maximum of 64 TX queues can be used with an
+    Intel XL710 Network Interface on a platform with more than 64 logical
+    cores. If a user attempts to add an XL710 interface as a DPDK port type to
+    a system as described above, an error will be reported that initialization
+    failed for the 65th queue. OVS will then roll back to the previous
+    successful queue initialization and use that value as the total number of
+    TX queues available with queue locking. If a user wishes to use more than
+    64 queues and avoid locking, then the
+    `CONFIG_RTE_LIBRTE_I40E_QUEUE_NUM_PER_PF` config parameter in DPDK must be
+    increased to the desired number of queues. Both DPDK and OVS must be
+    recompiled for this change to take effect.
 
   vHost and QEMU v2.4.0+:
   - For versions of QEMU v2.4.0 and later, it is currently not possible to