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Diffstat (limited to 'Documentation/networking/smc-sysctl.rst')
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diff --git a/Documentation/networking/smc-sysctl.rst b/Documentation/networking/smc-sysctl.rst new file mode 100644 index 000000000000..6d8acdbe9be1 --- /dev/null +++ b/Documentation/networking/smc-sysctl.rst @@ -0,0 +1,61 @@ +.. 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. + +smcr_testlink_time - INTEGER + How frequently SMC-R link sends out TEST_LINK LLC messages to confirm + viability, after the last activity of connections on it. Value 0 means + disabling TEST_LINK. + + Default: 30 seconds. + +wmem - INTEGER + Initial size of send buffer used by SMC sockets. + The default value inherits from net.ipv4.tcp_wmem[1]. + + The minimum value is 16KiB and there is no hard limit for max value, but + only allowed 512KiB for SMC-R and 1MiB for SMC-D. + + Default: 16K + +rmem - INTEGER + Initial size of receive buffer (RMB) used by SMC sockets. + The default value inherits from net.ipv4.tcp_rmem[1]. + + The minimum value is 16KiB and there is no hard limit for max value, but + only allowed 512KiB for SMC-R and 1MiB for SMC-D. + + Default: 128K |