netdev - [PATCH net-next 0/2] tcp: even faster connect() under stress

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Message-ID: <20250305034550.879255-1-edumazet@google.com>
Date: Wed,  5 Mar 2025 03:45:48 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: Neal Cardwell <ncardwell@...gle.com>, Kuniyuki Iwashima <kuniyu@...zon.com>, 
	Jason Xing <kernelxing@...cent.com>, Simon Horman <horms@...nel.org>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 0/2] tcp: even faster connect() under stress

This is a followup on the prior series, "tcp: scale connect() under pressure"

Now spinlocks are no longer in the picture, we see a very high cost
of the inet6_ehashfn() function.

In this series (of 2), I change how lport contributes to inet6_ehashfn()
to ensure better cache locality and call inet6_ehashfn()
only once per connect() system call.

This brings an additional 229 % increase of performance
for "neper/tcp_crr -6 -T 200 -F 30000" stress test,
while greatly improving latency metrics.

Before:
  latency_min=0.014131929
  latency_max=17.895073144
  latency_mean=0.505675853
  latency_stddev=2.125164772
  num_samples=307884
  throughput=139866.80

After:
  latency_min=0.003041375
  latency_max=7.056589232
  latency_mean=0.141075048
  latency_stddev=0.526900516
  num_samples=312996
  throughput=320677.21

Eric Dumazet (2):
  inet: change lport contribution to inet_ehashfn() and inet6_ehashfn()
  inet: call inet6_ehashfn() once from inet6_hash_connect()

 include/net/inet_hashtables.h |  4 +++-
 include/net/ip.h              |  2 +-
 net/ipv4/inet_hashtables.c    | 30 ++++++++++++++++++++----------
 net/ipv6/inet6_hashtables.c   | 19 +++++++++++++------
 4 files changed, 37 insertions(+), 18 deletions(-)

-- 
2.48.1.711.g2feabab25a-goog