linux/Documentation/networking/smc-sysctl.rst
Wen Gu 4bc5008e43 net/smc: Introduce a sysctl for setting SMC-R buffer type
This patch introduces the sysctl smcr_buf_type for setting
the type of SMC-R sndbufs and RMBs.

Valid values includes:

- SMCR_PHYS_CONT_BUFS, which means use physically contiguous
  buffers for better performance and is the default value.

- SMCR_VIRT_CONT_BUFS, which means use virtually contiguous
  buffers in case of physically contiguous memory is scarce.

- SMCR_MIXED_BUFS, which means first try to use physically
  contiguous buffers. If not available, then use virtually
  contiguous buffers.

Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-07-18 11:19:17 +01:00

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.. SPDX-License-Identifier: GPL-2.0
==========
SMC Sysctl
==========
/proc/sys/net/smc/* Variables
=============================
autocorking_size - INTEGER
Setting SMC auto corking size:
SMC auto corking is like TCP auto corking from the application's
perspective of view. When applications do consecutive small
write()/sendmsg() system calls, we try to coalesce these small writes
as much as possible, to lower total amount of CDC and RDMA Write been
sent.
autocorking_size limits the maximum corked bytes that can be sent to
the under device in 1 single sending. If set to 0, the SMC auto corking
is disabled.
Applications can still use TCP_CORK for optimal behavior when they
know how/when to uncork their sockets.
Default: 64K
smcr_buf_type - INTEGER
Controls which type of sndbufs and RMBs to use in later newly created
SMC-R link group. Only for SMC-R.
Default: 0 (physically contiguous sndbufs and RMBs)
Possible values:
- 0 - Use physically contiguous buffers
- 1 - Use virtually contiguous buffers
- 2 - Mixed use of the two types. Try physically contiguous buffers first.
If not available, use virtually contiguous buffers then.