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ethtool: Add support for configuring tx_push_buf_len

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This attribute, which is part of ethtool's ring param configuration
allows the user to specify the maximum number of the packet's payload
that can be written directly to the device.

Example usage:
    # ethtool -G [interface] tx-push-buf-len [number of bytes]

Co-developed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Shay Agroskin <shayagr@amazon.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Shay Agroskin
2023-03-23 18:36:05 +02:00
committed by Jakub Kicinski
parent 3e4d5ba9a3
commit 233eb4e786
6 changed files with 84 additions and 23 deletions
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8
Documentation/netlink/specs/ethtool.yaml
View File

@@ -165,6 +165,12 @@ attribute-sets:
-
name: rx-push
type: u8
-
name: tx-push-buf-len
type: u32
-
name: tx-push-buf-len-max
type: u32
-
name: mm-stat
@@ -311,6 +317,8 @@ operations:
- cqe-size
- tx-push
- rx-push
- tx-push-buf-len
- tx-push-buf-len-max
dump: *ring-get-op
-
name: rings-set

47
Documentation/networking/ethtool-netlink.rst
View File

@@ -860,22 +860,24 @@ Request contents:
Kernel response contents:
==================================== ====== ===========================
``ETHTOOL_A_RINGS_HEADER`` nested reply header
``ETHTOOL_A_RINGS_RX_MAX`` u32 max size of RX ring
``ETHTOOL_A_RINGS_RX_MINI_MAX`` u32 max size of RX mini ring
``ETHTOOL_A_RINGS_RX_JUMBO_MAX`` u32 max size of RX jumbo ring
``ETHTOOL_A_RINGS_TX_MAX`` u32 max size of TX ring
``ETHTOOL_A_RINGS_RX`` u32 size of RX ring
``ETHTOOL_A_RINGS_RX_MINI`` u32 size of RX mini ring
``ETHTOOL_A_RINGS_RX_JUMBO`` u32 size of RX jumbo ring
``ETHTOOL_A_RINGS_TX`` u32 size of TX ring
``ETHTOOL_A_RINGS_RX_BUF_LEN`` u32 size of buffers on the ring
``ETHTOOL_A_RINGS_TCP_DATA_SPLIT`` u8 TCP header / data split
``ETHTOOL_A_RINGS_CQE_SIZE`` u32 Size of TX/RX CQE
``ETHTOOL_A_RINGS_TX_PUSH`` u8 flag of TX Push mode
``ETHTOOL_A_RINGS_RX_PUSH`` u8 flag of RX Push mode
==================================== ====== ===========================
======================================= ====== ===========================
``ETHTOOL_A_RINGS_HEADER`` nested reply header
``ETHTOOL_A_RINGS_RX_MAX`` u32 max size of RX ring
``ETHTOOL_A_RINGS_RX_MINI_MAX`` u32 max size of RX mini ring
``ETHTOOL_A_RINGS_RX_JUMBO_MAX`` u32 max size of RX jumbo ring
``ETHTOOL_A_RINGS_TX_MAX`` u32 max size of TX ring
``ETHTOOL_A_RINGS_RX`` u32 size of RX ring
``ETHTOOL_A_RINGS_RX_MINI`` u32 size of RX mini ring
``ETHTOOL_A_RINGS_RX_JUMBO`` u32 size of RX jumbo ring
``ETHTOOL_A_RINGS_TX`` u32 size of TX ring
``ETHTOOL_A_RINGS_RX_BUF_LEN`` u32 size of buffers on the ring
``ETHTOOL_A_RINGS_TCP_DATA_SPLIT`` u8 TCP header / data split
``ETHTOOL_A_RINGS_CQE_SIZE`` u32 Size of TX/RX CQE
``ETHTOOL_A_RINGS_TX_PUSH`` u8 flag of TX Push mode
``ETHTOOL_A_RINGS_RX_PUSH`` u8 flag of RX Push mode
``ETHTOOL_A_RINGS_TX_PUSH_BUF_LEN`` u32 size of TX push buffer
``ETHTOOL_A_RINGS_TX_PUSH_BUF_LEN_MAX`` u32 max size of TX push buffer
======================================= ====== ===========================
``ETHTOOL_A_RINGS_TCP_DATA_SPLIT`` indicates whether the device is usable with
page-flipping TCP zero-copy receive (``getsockopt(TCP_ZEROCOPY_RECEIVE)``).
@@ -891,6 +893,18 @@ through MMIO writes, thus reducing the latency. However, enabling this feature
may increase the CPU cost. Drivers may enforce additional per-packet
eligibility checks (e.g. on packet size).
``ETHTOOL_A_RINGS_TX_PUSH_BUF_LEN`` specifies the maximum number of bytes of a
transmitted packet a driver can push directly to the underlying device
('push' mode). Pushing some of the payload bytes to the device has the
advantages of reducing latency for small packets by avoiding DMA mapping (same
as ``ETHTOOL_A_RINGS_TX_PUSH`` parameter) as well as allowing the underlying
device to process packet headers ahead of fetching its payload.
This can help the device to make fast actions based on the packet's headers.
This is similar to the "tx-copybreak" parameter, which copies the packet to a
preallocated DMA memory area instead of mapping new memory. However,
tx-push-buff parameter copies the packet directly to the device to allow the
device to take faster actions on the packet.
RINGS_SET
=========
@@ -908,6 +922,7 @@ Request contents:
``ETHTOOL_A_RINGS_CQE_SIZE`` u32 Size of TX/RX CQE
``ETHTOOL_A_RINGS_TX_PUSH`` u8 flag of TX Push mode
``ETHTOOL_A_RINGS_RX_PUSH`` u8 flag of RX Push mode
``ETHTOOL_A_RINGS_TX_PUSH_BUF_LEN`` u32 size of TX push buffer
==================================== ====== ===========================
Kernel checks that requested ring sizes do not exceed limits reported by