[PATCH v3 1/2] net/ixgbe: increase the maximum of RX/TX descriptors

[Lukas Sismis <sismis@cesnet.cz>]

Intel PMDs are capped by default to only 4096 RX/TX descriptors.
This can be limiting for applications requiring a bigger buffer
capabilities. By bufferring more packets with RX/TX
descriptors, the applications can better handle the processing
peaks.

Setting ixgbe max descriptors to 8192 as per datasheet:
Register name: RDLEN
Description: Descriptor Ring Length.
This register sets the number of bytes
allocated for descriptors in the circular descriptor buffer.
It must be 128B aligned (7 LS bit must be set to zero).
** Note: validated Lengths up to 128K (8K descriptors). **

Signed-off-by: Lukas Sismis <sismis@cesnet.cz>
---
 doc/guides/nics/ixgbe.rst        | 2 +-
 drivers/net/ixgbe/ixgbe_ethdev.c | 2 +-
 drivers/net/ixgbe/ixgbe_rxtx.h   | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
index 14573b542e..c5c6a6c34b 100644
--- a/doc/guides/nics/ixgbe.rst
+++ b/doc/guides/nics/ixgbe.rst
@@ -76,7 +76,7 @@ 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.
 
-By default, IXGBE_MAX_RING_DESC is set to 4096 and RTE_PMD_IXGBE_RX_MAX_BURST is set to 32.
+By default, IXGBE_MAX_RING_DESC is set to 8192 and RTE_PMD_IXGBE_RX_MAX_BURST is set to 32.
 
 Windows Prerequisites and Pre-conditions
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c b/drivers/net/ixgbe/ixgbe_ethdev.c
index 7da2ccf6a8..da9b3d7ca7 100644
--- a/drivers/net/ixgbe/ixgbe_ethdev.c
+++ b/drivers/net/ixgbe/ixgbe_ethdev.c
@@ -73,7 +73,7 @@
 
 #define IXGBE_MMW_SIZE_DEFAULT        0x4
 #define IXGBE_MMW_SIZE_JUMBO_FRAME    0x14
-#define IXGBE_MAX_RING_DESC           4096 /* replicate define from rxtx */
+#define IXGBE_MAX_RING_DESC           8192 /* replicate define from rxtx */
 
 /*
  *  Default values for RX/TX configuration
diff --git a/drivers/net/ixgbe/ixgbe_rxtx.h b/drivers/net/ixgbe/ixgbe_rxtx.h
index ee89c89929..0550c1da60 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx.h
+++ b/drivers/net/ixgbe/ixgbe_rxtx.h
@@ -25,7 +25,7 @@
  *      (num_ring_desc * sizeof(rx/tx descriptor)) % 128 == 0
  */
 #define	IXGBE_MIN_RING_DESC	32
-#define	IXGBE_MAX_RING_DESC	4096
+#define	IXGBE_MAX_RING_DESC	8192
 
 #define RTE_PMD_IXGBE_TX_MAX_BURST 32
 #define RTE_PMD_IXGBE_RX_MAX_BURST 32
-- 
2.34.1