Re: [Xen-devel] [PATCH] Network Checksum Removal

[Rolf Neugebauer <rolf.neugebauer@xxxxxxxxx>]

These results are pretty bad.

What do you get for dom0->external? That definitely should be close or equal
to native.

Have you tweaked /proc/sys/net/core/rmem_max?
Is the socket buffer set to some large value?
Are you transmitting/receiving enough data?

I don't know netperf but for ttcp I would normally do:

echo 1048576 > /proc/sys/net/core/rmem_max
ttcp -b 65536 (or similar) ...
And then transmit a few gigabytes

What's the interrupt rate etc.

Rolf


On 23/5/05 10:48 pm, "Bin Ren" <bin.ren@xxxxxxxxx> wrote:

> On 5/23/05, Nivedita Singhvi <niv@xxxxxxxxxx> 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.
> 
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