[net-next,0/4] inetpeer: reduce false sharing and atomic operations

Message

Eric Dumazet Dec. 13, 2024, 1:02 p.m. UTC

After commit 8c2bd38b95f7 ("icmp: change the order of rate limits"),
there is a risk that a host receiving packets from an unique
source targeting closed ports is using a common inet_peer structure
from many cpus.

All these cpus have to acquire/release a refcount and update
the inet_peer timestamp (p->dtime)

Switch to pure RCU to avoid changing the refcount, and update
p->dtime only once per jiffy.

Tested:
  DUT : 128 cores, 32 hw rx queues.
  receiving 8,400,000 UDP packets per second, targeting closed ports.

Before the series:
- napi poll can not keep up, NIC drops 1,200,000 packets
  per second. 
- We use 20 % of cpu cycles

After this series:
- All packets are received (no more hw drops)
- We use 12 % of cpu cycles.

Eric Dumazet (4):
  inetpeer: remove create argument of inet_getpeer_v[46]()
  inetpeer: remove create argument of inet_getpeer()
  inetpeer: update inetpeer timestamp in inet_getpeer()
  inetpeer: do not get a refcount in inet_getpeer()

 include/net/inetpeer.h | 12 +++++-------
 net/ipv4/icmp.c        |  6 +++---
 net/ipv4/inetpeer.c    | 29 ++++++++---------------------
 net/ipv4/ip_fragment.c | 15 ++++++++++-----
 net/ipv4/route.c       | 17 +++++++++--------
 net/ipv6/icmp.c        |  6 +++---
 net/ipv6/ip6_output.c  |  6 +++---
 net/ipv6/ndisc.c       |  8 +++++---
 8 files changed, 46 insertions(+), 53 deletions(-)