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net/smc: Introduce a specific sysctl for TEST_LINK time 

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 <guwen@linux.alibaba.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Wen Gu 2022-09-20 17:52:21 +08:00 committed by Paolo Abeni
parent 9b17dbd97d
commit 77eee32514
5 changed files with 19 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
Documentation/networking/smc-sysctl.rst
View File

@ -34,3 +34,10 @@ smcr_buf_type - INTEGER
- 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.

1
include/net/netns/smc.h
View File

@ -19,5 +19,6 @@ struct netns_smc {
#endif
unsigned int sysctl_autocorking_size;
unsigned int sysctl_smcr_buf_type;
int sysctl_smcr_testlink_time;
};
#endif

2
net/smc/smc_llc.c
View File

@ -2127,7 +2127,7 @@ void smc_llc_lgr_init(struct smc_link_group *lgr, struct smc_sock *smc)
init_waitqueue_head(&lgr->llc_flow_waiter);
init_waitqueue_head(&lgr->llc_msg_waiter);
mutex_init(&lgr->llc_conf_mutex);
lgr->llc_testlink_time = READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time);
lgr->llc_testlink_time = READ_ONCE(net->smc.sysctl_smcr_testlink_time);
}
/* called after lgr was removed from lgr_list */

1
net/smc/smc_llc.h
View File

@ -19,6 +19,7 @@
#define SMC_LLC_WAIT_FIRST_TIME (5 * HZ)
#define SMC_LLC_WAIT_TIME (2 * HZ)
#define SMC_LLC_TESTLINK_DEFAULT_TIME (30 * HZ)
enum smc_llc_reqresp {
SMC_LLC_REQ,

9
net/smc/smc_sysctl.c
View File

@ -16,6 +16,7 @@
#include "smc.h"
#include "smc_core.h"
#include "smc_llc.h"
#include "smc_sysctl.h"
static struct ctl_table smc_table[] = {
@ -35,6 +36,13 @@ static struct ctl_table smc_table[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_TWO,
},
{
.procname = "smcr_testlink_time",
.data = &init_net.smc.sysctl_smcr_testlink_time,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
{ }
};
@ -60,6 +68,7 @@ int __net_init smc_sysctl_net_init(struct net *net)
net->smc.sysctl_autocorking_size = SMC_AUTOCORKING_DEFAULT_SIZE;
net->smc.sysctl_smcr_buf_type = SMCR_PHYS_CONT_BUFS;
net->smc.sysctl_smcr_testlink_time = SMC_LLC_TESTLINK_DEFAULT_TIME;
return 0;