Re: RFC: NAPI packet weighting patch

[P@xxxxxxxxxxxxxx]

jamal wrote:
> On Wed, 2005-22-06 at 09:42 +0100, P@xxxxxxxxxxxxxx wrote:
>
>
> > Yes the copy is essentially free here as the data is already cached.
> >
> > As a data point, I went the whole hog and used buffer recycling
> > in my essentially packet sniffing application. I.E. there are no
> > allocs per packet at all, and this make a HUGE difference. On a
> > 2x3.4GHz 2xe1000 system I can receive 620Kpps per port sustained
> > into my userspace app which does a LOT of processing per packet.
> > Without the buffer recycling is was around 250Kpps.
> > Note I don't reuse an skb until the packet is copied into a
> > PACKET_MMAP buffer.
>
> Was this machine SMP?
Yes. 2 x 3.4GHz P4s
1 logical CPU per port (irq affinity)
1 thread (NB on same logical CPU as irq (sched_affinity))
to do user space per packet processing.

> NAPI involved?
Yep.

> I take it nothing interfering in
> the middle with the headers?
It uses the standard path to PACKET_MMAP buffer
e1000_clean_rx_irq -> netif_receive_skb -> tpacket_rcv

Pádraig.