Re: [PATCH net-next 17/20] tcp: defer skb freeing after socket lock is released

On Tue, 16 Nov 2021 08:46:37 -0800 Eric Dumazet wrote:

On my testing host,

4K MTU : processing ~2,600.000 packets per second in GRO and other parts
use about 60% of the core in BH.
(Some of this cost comes from a clang issue, and the csum_partial() one
I was working on last week)
NIC RX interrupts are firing about 25,000 times per second in this setup.

1500 MTU : processing ~ 5,800,000 packets per second uses one core in
BH (and also one core in recvmsg()),
We stay in NAPI mode (no IRQ rearming)
(That was with a TCP_STREAM run sustaining 70Gbit)

BH numbers also depend on IRQ coalescing parameters.

Very interesting, curious to see what not doing the copy under socket
lock will do to the 1.5k case. 

Thanks a lot for sharing the detailed info!