Re: [PATCH] Network Checksum Removal

[Bin Ren <bin.ren@gmail.com>]

On 5/23/05, Nivedita Singhvi <niv@us.ibm.com> wrote:
> 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.

I've given all the domains 256M memory and switched to netperf
TCP_STREAM (netperf -H server). almost no change. Details:

dom1->external: 420Mbps
dom1->dom0: 437Mbps
dom0->dom1: 200Mbps (!!!)
dom1->dom2: 327Mbps

>  
> > 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?

Please see above.