The minimum free packet threshold (tx_free_thresh) and the minimum RS bit
threshold (tx_rs_thresh) both have a default value of 32. Therefore, the
default minimum number of ring descriptors value is 64.
For reference, see "Configuration of Transmit Queues" in
doc/guides/prog_guide/ethdev/ethdev.rst
Fixes: dee5f1fd5fc7 ("ixgbe: get queue info and descriptor limits")
Cc: sta...@dpdk.org
Signed-off-by: Mingjin Ye <mingjinx...@intel.com>
---
v2: Change doc.
---
doc/guides/nics/ixgbe.rst | 5 +++--
drivers/net/intel/ixgbe/ixgbe_rxtx.h | 2 +-
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
index c5c6a6c34b..aaed324e15 100644
--- a/doc/guides/nics/ixgbe.rst
+++ b/doc/guides/nics/ixgbe.rst
@@ -68,11 +68,12 @@ Ensure that the following pre-conditions are satisfied:
* (rxq->nb_rx_desc % rxq->rx_free_thresh) == 0
-* rxq->nb_rx_desc < (IXGBE_MAX_RING_DESC - RTE_PMD_IXGBE_RX_MAX_BURST)
+* rxq->nb_rx_desc >= IXGBE_MIN_RING_DESC
+
+* rxq->nb_rx_desc <= IXGBE_MAX_RING_DESC
These conditions are checked in the code.
-Scattered packets are not supported in this mode.
If an incoming packet is greater than the maximum acceptable length of one
"mbuf" data size (by default, the size is 2 KB),
vPMD for RX would be disabled.
diff --git a/drivers/net/intel/ixgbe/ixgbe_rxtx.h
b/drivers/net/intel/ixgbe/ixgbe_rxtx.h
index 278f665108..54569c7ade 100644
--- a/drivers/net/intel/ixgbe/ixgbe_rxtx.h
+++ b/drivers/net/intel/ixgbe/ixgbe_rxtx.h
@@ -26,7 +26,7 @@
* descriptors should meet the following condition:
* (num_ring_desc * sizeof(rx/tx descriptor)) % 128 == 0
*/
-#define IXGBE_MIN_RING_DESC 32
+#define IXGBE_MIN_RING_DESC 64
#define IXGBE_MAX_RING_DESC 8192
#define RTE_PMD_IXGBE_TX_MAX_BURST 32
--
2.25.1
