[PATCH] doc: improve event core description in vDPA mlx5

[Matan Azrad]

The event core is mlx5 vDPA driver devarg that selects the CPU core for
the internal timer thread used to manage data-path events into the
driver.

Emphasize that this CPU should be isolated for vDPA mlx5 devices only in
order to save the performance and latency of the device.

Signed-off-by: Matan Azrad <matan at nvidia.com>
---
 doc/guides/vdpadevs/mlx5.rst | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/doc/guides/vdpadevs/mlx5.rst b/doc/guides/vdpadevs/mlx5.rst
index 9767fbe42d..3b5ce6df38 100644
--- a/doc/guides/vdpadevs/mlx5.rst
+++ b/doc/guides/vdpadevs/mlx5.rst
@@ -86,8 +86,13 @@ for an additional list of options shared with other mlx5 drivers.
 
 - ``event_core`` parameter [int]
 
-  CPU core number to set polling thread affinity to, default to control plane
-  cpu.
+  The CPU core number of the timer thread, default: EAL main lcore.
+
+.. note::
+
+   This core can be shared among different mlx5 vDPA devices as `event_core` but
+   using it also for other tasks may affect the performance and the latency of the
+   mlx5 vDPA devices.
 
 - ``max_conf_threads`` parameter [int]
 
-- 
2.25.1