From: Jakub Kicinski 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 Signed-off-by: Pavel Begunkov --- 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