From: Jakub Kicinski <kuba@kernel.org>
Document the semantics of the rx_buf_len ethtool ring param.
Clarify its meaning in case of HDS, where driver may have
two separate buffer pools.
The various zero-copy TCP Rx schemes we have suffer from memory
management overhead. Specifically applications aren't too impressed
with the number of 4kB buffers they have to juggle. Zero-copy
TCP makes most sense with larger memory transfers so using
16kB or 32kB buffers (with the help of HW-GRO) feels more
natural.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
Documentation/networking/ethtool-netlink.rst | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
index ab20c644af24..cae372f719d1 100644
--- a/Documentation/networking/ethtool-netlink.rst
+++ b/Documentation/networking/ethtool-netlink.rst
@@ -966,7 +966,6 @@ Kernel checks that requested ring sizes do not exceed limits reported by
driver. Driver may impose additional constraints and may not support all
attributes.
-
``ETHTOOL_A_RINGS_CQE_SIZE`` specifies the completion queue event size.
Completion queue events (CQE) are the events posted by NIC to indicate the
completion status of a packet when the packet is sent (like send success or
@@ -980,6 +979,11 @@ completion queue size can be adjusted in the driver if CQE size is modified.
header / data split feature. If a received packet size is larger than this
threshold value, header and data will be split.
+``ETHTOOL_A_RINGS_RX_BUF_LEN`` controls the size of the buffers driver
+uses to receive packets. If the device uses different buffer pools for
+headers and payload (due to HDS, HW-GRO etc.) this setting must
+control the size of the payload buffers.
+
CHANNELS_GET
============
--
2.49.0