On Fri, Jul 6, 2012 at 9:57 PM, Emeric Vigier <[email protected]> wrote:
> I don't think it is the same problem. My ethernet TX gets stuck stuck to
> 10-20KBps (80-160Kbps). When I force some activity (USB mouse events) it
> can reach ~1MBps (8Mbps). Also the interface is supposed to (and says
> to) be 100Mbps...
>
> I opened a thread on various mailing-lists:
> http://comments.gmane.org/gmane.linux.network/234335
>
> I saw your ehci patch on this thread:
> https://patchwork.kernel.org/patch/1113332/
>
> The thing is, my kernel already includes your patch. I also included
> Will Deacon's patch in process.c (cpu_idle), the one you mentioned here.
>
> But I have some reasons to believe that none of the patches are suited in my 
> case because:
> 1. Ethernet TX performance is still very bad with these patches and 
> corresponding configs,
> 2. smsc95xx driver relies on usbnet. I think that usbnet uses interrupt for 
> RX but not for TX. Then flushing the caches with wmb() just before entering 
> idle (WFI in my case) won't be efficient for me as ethernet TX has no way to 
> wake-up the cpu, it has to wait for an external wakeup source. USB Mouse 
> event improves TX performance.
> 3. I cannot state whether your patch in ehci-q.c "should" work for me, 
> because I don't know if (TX) URB submission in usbnet finally goes through 
> this file's functions or another.
>
> Do you know if my statements above make sense? Do you know where I
> should put the memory barrier and test again in my particular case?


OK, I don't suggest that you do some blind test further without knowing
the reason.

Could you provide the trace result according to the guide in
Documentation/usb/usbmon.txt or the link[1]?

[1], http://www.mjmwired.net/kernel/Documentation/usb/usbmon.txt

thanks,
--
Ming Lei

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https://bugs.launchpad.net/bugs/709245

Title:
  ARM SMP scheduler performance bug

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