xref: /linux/Documentation/networking/smc-sysctl.rst (revision 4b660dbd9ee2059850fd30e0df420ca7a38a1856)
1.. SPDX-License-Identifier: GPL-2.0
2
3==========
4SMC Sysctl
5==========
6
7/proc/sys/net/smc/* Variables
8=============================
9
10autocorking_size - INTEGER
11	Setting SMC auto corking size:
12	SMC auto corking is like TCP auto corking from the application's
13	perspective of view. When applications do consecutive small
14	write()/sendmsg() system calls, we try to coalesce these small writes
15	as much as possible, to lower total amount of CDC and RDMA Write been
16	sent.
17	autocorking_size limits the maximum corked bytes that can be sent to
18	the under device in 1 single sending. If set to 0, the SMC auto corking
19	is disabled.
20	Applications can still use TCP_CORK for optimal behavior when they
21	know how/when to uncork their sockets.
22
23	Default: 64K
24
25smcr_buf_type - INTEGER
26        Controls which type of sndbufs and RMBs to use in later newly created
27        SMC-R link group. Only for SMC-R.
28
29        Default: 0 (physically contiguous sndbufs and RMBs)
30
31        Possible values:
32
33        - 0 - Use physically contiguous buffers
34        - 1 - Use virtually contiguous buffers
35        - 2 - Mixed use of the two types. Try physically contiguous buffers first.
36          If not available, use virtually contiguous buffers then.
37
38smcr_testlink_time - INTEGER
39	How frequently SMC-R link sends out TEST_LINK LLC messages to confirm
40	viability, after the last activity of connections on it. Value 0 means
41	disabling TEST_LINK.
42
43	Default: 30 seconds.
44
45wmem - INTEGER
46	Initial size of send buffer used by SMC sockets.
47
48	The minimum value is 16KiB and there is no hard limit for max value, but
49	only allowed 512KiB for SMC-R and 1MiB for SMC-D.
50
51	Default: 64KiB
52
53rmem - INTEGER
54	Initial size of receive buffer (RMB) used by SMC sockets.
55
56	The minimum value is 16KiB and there is no hard limit for max value, but
57	only allowed 512KiB for SMC-R and 1MiB for SMC-D.
58
59	Default: 64KiB
60
61smcr_max_links_per_lgr - INTEGER
62	Controls the max number of links can be added to a SMC-R link group. Notice that
63	the actual number of the links added to a SMC-R link group depends on the number
64	of RDMA devices exist in the system. The acceptable value ranges from 1 to 2. Only
65	for SMC-R v2.1 and later.
66
67	Default: 2
68
69smcr_max_conns_per_lgr - INTEGER
70	Controls the max number of connections can be added to a SMC-R link group. The
71	acceptable value ranges from 16 to 255. Only for SMC-R v2.1 and later.
72
73	Default: 255
74