On Feb 4, 2011, at 1:15 PM, Conrad Wood wrote:

> 
> On 4 Feb 2011, at 19:31, Doug Hughes wrote:
> 
>> On 2/4/2011 1:11 PM, Conrad Wood wrote:
>>> 
>>>> Re: 7gbits/etc. As others have said, you're over-running your CPU. IP
>>>> over IB works just fine, but the packet sizes aren't matched up. What
>>>> you really want to do is test it using actual native infiniband
>>>> protocols. I recommend the Intel Benchmark Suite (IBM - nee Pallas). It
>>>> will test infiniband typical MPI operations.
>>> Fair enough, problem is, I am trying to provide highspeed internet access 
>>> to clients and they need tcp/ip (only). So I got to improve the speed of 
>>> IPoIB.
>>> And yes, we have>20GBit/s internet connectivity.
>>> 
>> parallel sessions on more than one CPU core. try iperf -P 4, or -P 8.
>> if they have more than one session going simultaneously, they get this 
>> automatically (mostly)
>> 
>> 
> 
> in my tests, parallel threads on the same machine did (in total) not exceed 
> 7GBit/s either.
> there seems to be a single-threaded bottleneck somewhere.
> Also, this won't help if clients do a single HTTP download.
> So I am still trying to maximise TCP throughput.
> I can (roughly) reproduce skylars finding so will work on the kernel code to 
> optimise performance and scale it across multiple cores as I reckon that's 
> where our bottleneck is.

Are you sure that the IB nic is plugged into a fully wired pci-e slot? This 
speed sounds suspiciously like what you could expect from a gen1 x4 pci-e slot 
after overhead.
 -nld
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