On 05/23/2014 02:33 AM, Bjørn Mork wrote:
Jim Baxter <jim_baxter@xxxxxxxxxx> writes:
I'll create and test a patch for the cdc_ncm host driver unless someone
else wants to do that. I haven't really played with the gadget driver
before, so I'd prefer if someone knowing it (Jim maybe?) could take care
of it. If not, then I can always make an attempt using dummy_hcd to
test it.
I can create a patch for the host driver, I will issue the gadget patch
first to resolve any issues, the fix would be similar.
Well, I couldn't help myself. I just had to test it. The attached
patch works for me, briefly tested with an Ericsson H5321gw NCM device.
I have no ideas about the performance impact as that modem is limited to
21 Mbps HSDPA.
If you are measuring performance with the likes of netperf, you should
be able to get an idea of the performance effect from the change in
service demand (CPU consumed per unit of work) even if the maximum
throughput remains capped.
You can run a netperf TCP_STREAM test along the lines of:
netperf -H <otherguy> -c -C -t TCP_STREAM
and also
netperf -H <otherguy> -c -C -t TCP_RR
For extra added credit you can consider either multiple runs and
post-processing, or adding a -i 30,3 to the command line to tell netperf
to run at least three iterations, no more than thirty and it will try to
achieve a 99% confidence that the reported means for throughput, local
and remote CPU utilization are within +/- 2.5% of the actual mean. You
can narrow or widen that with a -I 99,<width>. A width of 5% is what
gives the +/- 2.5% (and/or demonstrates my lack of accurate statistics
knowledge :) )
happy benchmarking,
rick jones
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