PSP 3.21 has worse performances than PSP 3.20

Qmax

Other Parts Discussed in Thread: AM1808

Dear TI experts,

I'm running some iperf tests on AM1808 Exp Kit board, using USB CDC/RNDIS as network interface (gadget g_ether).

First, I've run tests with SDK the board come with: kernel 2.6.33 PSP 3.20.0.14. Then I run the same tests with kernel 2.6.37 PSP 3.21.0.4 from the latest SDK 05.03.02.00: results are worse, heavily worse! With iperf server running on the device (AM1808) and iperf client on host (Linux PC), the results are approx:

PSP 3.20.0.14 : 65 Mbps

PSP 3.21.0.04 : less than 40 Mbps

In both cases I've used the default kernel configuration (da850...), just changing the USB 2.0 controller to work as peripheral, and adding gadget module build. And CPPI41 DMA support for MUSB is enabled in both cases, too.

How can you explain that?

I've look at performance guides for PSP 3.20 and PSP 3.21: degradation is evident also from those numbers, but less than what I have verified.

Hope someone could clarify.
Thanks in advance.

Regards, Max

over 13 years ago

0 Ajay over 13 years ago

TI__Genius 9460 points

Max,

We have also seen performance drop across drivers on v2.6.37 kernel. So far I am not aware of any solution or fixes to it.

Ajay

0 kadir yasar over 13 years ago in reply to Ajay

Intellectual 730 points

I live the same problem on v2.6.37. There may be two solutions of this issue. At first, I applied BFS (Brain *** Scheduler -http://ck.kolivas.org/patches/bfs/) patch and network performance jumped from 30 Mbits/sec to 49.5 Mbits/sec in CDC mode without DMA (if you can try it with DMA enabled and BFS patch, let me know the result). Not only network perf. but also process scheduleing latency is decreased (this also means better performance). Secondly, as of 2.6.37 (https://lkml.org/lkml/2011/3/30/836), kworkers are used as kernel worker threads for inner kernel jobs like interrupts, timer, io.. you should check your ps and look at the cpu usage of kworkers if they are much, try to find cause. (http://e2e.ti.com/support/embedded/linux/f/354/p/190794/683764.aspx)

Thanks

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PSP 3.21 has worse performances than PSP 3.20