netdev - [RFC net-next 0/2] Optimize the parallelism of SMC-R connections

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Message-Id: <1694008530-85087-1-git-send-email-alibuda@linux.alibaba.com>
Date: Wed,  6 Sep 2023 21:55:28 +0800
From: "D. Wythe" <alibuda@...ux.alibaba.com>
To: kgraul@...ux.ibm.com,
	wenjia@...ux.ibm.com,
	jaka@...ux.ibm.com
Cc: kuba@...nel.org,
	davem@...emloft.net,
	netdev@...r.kernel.org,
	linux-s390@...r.kernel.org,
	linux-rdma@...r.kernel.org,
	"D. Wythe" <alibuda@...ux.alibaba.com>
Subject: [RFC net-next 0/2] Optimize the parallelism of SMC-R connections 

From: "D. Wythe" <alibuda@...ux.alibaba.com>

This patchset attempts to optimize the parallelism of SMC-R connections
in quite a SIMPLE way, reduce unnecessary blocking on locks.

According to Off-CPU statistics, SMC worker's off-CPU statistics
as that: 

smc_listen_work 			(48.17%)
	__mutex_lock.isra.11 		(47.96%)

An ideal SMC-R connection process should only block on the IO events
of the network, but it's quite clear that the SMC-R connection now is
queued on the lock most of the time.

Before creating a connection, we always try to see if it can be
successfully created without allowing the creation of an lgr,
if so, it means it does not rely on new link group.
In other words, locking on xxx_lgr_pending is not necessary
any more.

Noted that removing this lock will not have an immediate effect
in the current version, as there are still some concurrency issues
in the SMC handshake phase. However, regardless, removing this lock
is a prerequisite for other optimizations.

If you have any questions or suggestions, please let me know.

D. Wythe (2):
  net/smc: refactoring lgr pending lock
  net/smc: remove locks smc_client_lgr_pending and
    smc_server_lgr_pending

 net/smc/af_smc.c   | 24 ++++++++++++------------
 net/smc/smc_clc.h  |  1 +
 net/smc/smc_core.c | 28 ++++++++++++++++++++++++++--
 net/smc/smc_core.h | 21 +++++++++++++++++++++
 4 files changed, 60 insertions(+), 14 deletions(-)

-- 
1.8.3.1