Re: RFC: NAPI packet weighting patch

[Stephen Hemminger <shemminger@xxxxxxxx>]

> I have profile data, here is an example of 5tx/5rx threads, where the 
> throughput was 1236Mb/s total, 936tx, 300rx, on 2.6.12-rc5 with old TSO 
> (the original problem case) we are at 100% cpu and generating 3289 ints/s, 
> with no hardware drops reported prolly due to my replenish patch
> CPU: P4 / Xeon with 2 hyper-threads, speed 2791.36 MHz (estimated)
> Counted GLOBAL_POWER_EVENTS events (time during which processor is not 
> stopped) with a unit mask of 0x01 (mandatory) count 100000
> samples  %        image name       symbol name
> 533687    8.1472  vmlinux          pskb_expand_head
> 428726    6.5449  vmlinux          __copy_user_zeroing_intel
> 349934    5.3421  vmlinux          _read_lock_irqsave

We should kill all reader/writer locks in the fastpath. reader locks are
more expensive than spinlocks unless they are going to be held for a fairly
large window.


> 313667    4.7884  vmlinux          csum_partial
> 218870    3.3413  vmlinux          _spin_lock
> 214302    3.2715  vmlinux          __copy_user_intel
> 193662    2.9564  vmlinux          skb_release_data
> 177755    2.7136  vmlinux          ipt_do_table

You are probably benchmarking iptables/netfilter! How many rules do you
have?