Commit 77eee325 authored by Wen Gu's avatar Wen Gu Committed by Paolo Abeni
Browse files

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: default avatarWen Gu <guwen@linux.alibaba.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 9b17dbd9

Documentation/networking/smc-sysctl.rst

+7 −0
Original line number Diff line number Diff line
@@ -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.

include/net/netns/smc.h

+1 −0
Original line number Diff line number Diff line
@@ -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

net/smc/smc_llc.c

+1 −1
Original line number Diff line number Diff line
@@ -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 */

net/smc/smc_llc.h

+1 −0
Original line number Diff line number Diff line
@@ -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,

net/smc/smc_sysctl.c

+9 −0
Original line number Diff line number Diff line
@@ -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;