Re: [E1000-devel] Transmission limit

[Marco Mellia <mellia@xxxxxxxxxxxxxxxxxxxx>]

On Wed, 2004-12-01 at 02:09, Scott Feldman wrote:
> Hey, turns out, I know some e1000 tricks that might help get the kpps
> numbers up.  
> 
> My problem is I only have a P4 desktop system with a 82544 nic running
> at PCI 32/33Mhz, so I can't play with the big boys.  But, attached is a
> rework of the Tx path to eliminate 1) Tx interrupts, and 2) Tx
> descriptor write-backs.  For me, I see a nice jump in kpps, but I'd like
> others to try with their setups.  We should be able to get to wire speed
> with 60-byte packets.
> 

Here are the numbers in our setup:

vanilla kernel [2.4.20 + packetgen + driver e1000 5.4.11]
4096 Descr => 356 Mbps (60 bytes long frames)
           => 941Mbps (1500 bytes lonf frames)

256 Descr => 354 Mbps (60 bytes long frames)
           => 941Mbps (1500 bytes lonf frames)

Patched driver [2.4.20 + packetgen + driver e1000 5.4.11 patched]
4096 Descr => 357 Mbps (60 bytes long frames)
           => 941Mbps (1500 bytes lonf frames)

I guess that was _not_ the bottleneck sigh... at least with a PCI-X bus.
Again, latency issue of the DMA transfer from RAM to NIC?

-- 
Ciao,                    /\/\/\rco

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