Re: [PATCH] Network Checksum Removal

[Nivedita Singhvi <niv@us.ibm.com>]

Bin Ren wrote:
> I've added the support for ethtools. By turning on and off netfront
> checksum offloading, I'm getting the following throughput numbers,
> using iperf. Each test was run three times. CPU usages are quite
> similar in two cases ('top' output). Looks like checksum computation
> is not a major overhead in domU networking.
> 
> dom0/1/2 all have 128M memory. dom0 has e1000 tx checksum offloading turned on.

Yeah, if you want to do anything network intensive, 128MB is just
not enough - you really need more memory in your system.


> With Tx checksum on:
> 
> dom1->dom2: 300Mb/s (dom0 cpu maxed out by software interrupts)
> dom1->dom0: 459Mb/s (dom0 cpu 80% in SI, dom1 cpu 20% in SI)
> dom1->external: 439Mb/s (over 1Gb/s ethernet) (dom0 cpu 50% in SI,
> dom1 60% in SI)
> 
> With Tx checksum off:
> 
> dom1->dom2: 301Mb/s
> dom1->dom0: 454Mb/s
> dom1->externel: 437Mb/s (over 1Gb/s ethernet)


iperf is a directional send test, correct?
i.e. is dom1 -> dom0 perf the same as dom0 -> dom1 for you?

thanks,
Nivedita