linux-toradex.git/Documentation/networking/smc-sysctl.rst, branch v6.7

net/smc: fix documentation of buffer sizes

2023-11-02T11:50:17+00:00

Since commit 833bac7ec392 ("net/smc: Fix setsockopt and sysctl to
specify same buffer size again") the SMC protocol uses its own
default values for the smc.rmem and smc.wmem sysctl variables
which are no longer derived from the TCP IPv4 buffer sizes.

Fixup the kernel documentation to reflect this change, too.

Fixes: 833bac7ec392 ("net/smc: Fix setsockopt and sysctl to specify same buffer size again")
Signed-off-by: Gerd Bayer 
Reviewed-by: Wenjia Zhang 
Reviewed-by: Dust Li 
Link: https://lore.kernel.org/r/20231030170343.748097-1-gbayer@linux.ibm.com
Signed-off-by: Paolo Abeni

net/smc: Unbind r/w buffer size from clcsock and make them tunable

2022-09-22T10:58:21+00:00

Currently, SMC uses smc->sk.sk_{rcv|snd}buf to create buffers for
send buffer and RMB. And the values of buffer size are from tcp_{w|r}mem
in clcsock.

The buffer size from TCP socket doesn't fit SMC well. Generally, buffers
are usually larger than TCP for SMC-R/-D to get higher performance, for
they are different underlay devices and paths.

So this patch unbinds buffer size from TCP, and introduces two sysctl
knobs to tune them independently. Also, these knobs are per net
namespace and work for containers.

Signed-off-by: Tony Lu 
Signed-off-by: Paolo Abeni

net/smc: Introduce a specific sysctl for TEST_LINK time

2022-09-22T10:58:21+00:00

SMC-R tests the viability of link by sending out TEST_LINK LLC
messages over RoCE fabric when connections on link have been
idle for a time longer than keepalive interval (testlink time).

But using tcp_keepalive_time as testlink time maybe not quite
suitable because it is default no less than two hours[1], which
is too long for single link to find peer dead. The active host
will still use peer-dead link (QP) sending messages, and can't
find out until get IB_WC_RETRY_EXC_ERR error CQEs, which takes
more time than TEST_LINK timeout (SMC_LLC_WAIT_TIME) normally.

So this patch introduces a independent sysctl for SMC-R to set
link keepalive time, in order to detect link down in time. The
default value is 30 seconds.

[1] https://www.rfc-editor.org/rfc/rfc1122#page-101

Signed-off-by: Wen Gu 
Signed-off-by: Paolo Abeni

net/smc: Introduce a sysctl for setting SMC-R buffer type

2022-07-18T10:19:17+00:00

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 
Signed-off-by: David S. Miller

net/smc: fix document build WARNING from smc-sysctl.rst

2022-03-04T05:24:34+00:00

Stephen reported the following warning messages from smc-sysctl.rst

Documentation/networking/smc-sysctl.rst:3: WARNING: Title overline
too short.
Documentation/networking/smc-sysctl.rst: WARNING: document isn't
included in any toctree

Fix the title overline and add smc-sysctl entry into
Documentation/networking/index.rst

Fixes: 12bbb0d163a9 ("net/smc: add sysctl for autocorking")
Reported-by: Stephen Rothwell 
Signed-off-by: Dust Li 
Link: https://lore.kernel.org/r/20220303113527.62047-1-dust.li@linux.alibaba.com
Signed-off-by: Jakub Kicinski

net/smc: add sysctl for autocorking

2022-03-01T14:25:12+00:00

This add a new sysctl: net.smc.autocorking_size

We can dynamically change the behaviour of autocorking
by change the value of autocorking_size.
Setting to 0 disables autocorking in SMC

Signed-off-by: Dust Li 
Signed-off-by: David S. Miller