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| author | Jakub Kicinski <kuba@kernel.org> | 2025-03-05 04:46:30 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-03-05 04:46:30 +0300 |
| commit | 85f66df39bcfc0b35f0b068f281b17c8811342c5 (patch) | |
| tree | d798c722eef0e5158040b5825250f3053d183384 /net/lapb/lapb_out.c | |
| parent | 7ff1c88fc89688c27f773ba956f65f0c11367269 (diff) | |
| parent | 86c2bc293b8130aec9fa504e953531a84a6eb9a6 (diff) | |
| download | linux-85f66df39bcfc0b35f0b068f281b17c8811342c5.tar.xz | |
Merge branch 'tcp-scale-connect-under-pressure'
Eric Dumazet says:
====================
tcp: scale connect() under pressure
Adoption of bhash2 in linux-6.1 made some operations almost twice
more expensive, because of additional locks.
This series adds RCU in __inet_hash_connect() to help the
case where many attempts need to be made before finding
an available 4-tuple.
This brings a ~200 % improvement in this experiment:
Server:
ulimit -n 40000; neper/tcp_crr -T 200 -F 30000 -6 --nolog
Client:
ulimit -n 40000; neper/tcp_crr -T 200 -F 30000 -6 --nolog -c -H server
Before series:
utime_start=0.288582
utime_end=1.548707
stime_start=20.637138
stime_end=2002.489845
num_transactions=484453
latency_min=0.156279245
latency_max=20.922042756
latency_mean=1.546521274
latency_stddev=3.936005194
num_samples=312537
throughput=47426.00
perf top on the client:
49.54% [kernel] [k] _raw_spin_lock
25.87% [kernel] [k] _raw_spin_lock_bh
5.97% [kernel] [k] queued_spin_lock_slowpath
5.67% [kernel] [k] __inet_hash_connect
3.53% [kernel] [k] __inet6_check_established
3.48% [kernel] [k] inet6_ehashfn
0.64% [kernel] [k] rcu_all_qs
After this series:
utime_start=0.271607
utime_end=3.847111
stime_start=18.407684
stime_end=1997.485557
num_transactions=1350742
latency_min=0.014131929
latency_max=17.895073144
latency_mean=0.505675853 # Nice reduction of latency metrics
latency_stddev=2.125164772
num_samples=307884
throughput=139866.80 # 194 % increase
perf top on client:
56.86% [kernel] [k] __inet6_check_established
17.96% [kernel] [k] __inet_hash_connect
13.88% [kernel] [k] inet6_ehashfn
2.52% [kernel] [k] rcu_all_qs
2.01% [kernel] [k] __cond_resched
0.41% [kernel] [k] _raw_spin_lock
====================
Link: https://patch.msgid.link/20250302124237.3913746-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/lapb/lapb_out.c')
0 files changed, 0 insertions, 0 deletions