INSTALL.DPDK.md: Add details of XL710 restrictions for DPDK

Currently there are restrictions regarding the use of the XL710 network
interface with OVS and DPDK. This patch details those restrictions in
INSTALL.DPDK.md.

Signed-off-by: Ian Stokes <ian.stokes@intel.com>
Signed-off-by: Ethan Jackson <ethan@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>

diff --git a/INSTALL.DPDK.md b/INSTALL.DPDK.md
index 1287fea..639ee37 100644 (file)
--- a/INSTALL.DPDK.md
+++ b/INSTALL.DPDK.md
@@ -720,6 +720,19 @@ Restrictions:
     want to share dpdkr rings with other processes on the host, you can do
     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.
+
 Bug Reporting:
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