Re: [PATCH v2 net-next] tcp: avoid expensive pskb_expand_head() calls

Rick Jones
2012-04-19T18:05:52Z

>> That or bare ACKs have to be excluded from the overhead checks somehow I
>> guess, or there be more aggressive copying into smaller buffers.
>>
>
> Nope, we need a limit or risk OOM if a malicious peer send ACK flood ;)

Well, there is that...

>
> To be clear, if I change the tcp_rmem[1] from 87380 to big value, I no
> longer have ACK drops, but still poor performance, I am still
> investigating.

What happens if you set net.core.[rw]mem_max to 4 MB and then use
something like -s 1M -S 1M in netperf?

netperf -t TCP_STREAM -H <remote> -- -s 1M -S 1M -m 64K

(or -m 16K if you want to keep the send size the same as your previous
tests...)

rick