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Re: Forw: RE: systemtap with USB
Hello,
On Tue, 3 Jun 2008 20:58:01 -0700 (PDT), tsjaseen
<jaseen.shamsuddin@wipro.com> wrote:
> I would like to experiment more on this to see what all can be tapped
from
> the USB subsystem. Please suggest how to proceed so that we can make some
> contribution on this side.
The simplest thing to do would be to track down all the function calls
starting form usb_register_driver. If you look at the implementation
of usb_register_driver [1] you can start thinking on how to do it.
Just follow the function call and print each one using thread_indent()
so it's easier to read. After that you could start trying to identify
hot paths in the middle and check if they could be optimized or not.
Also, checking usb throughput each 5 secs, or something, and printing
the exact function been called now would, maybe, help identifying wether
we should or shouldn't improve the code.
USB 2.0 devices attached to USB 2.0 hosts (ehci) could transfer
at a rate of 480Mbps, something around 300Mbps still quite acceptable,
but 60Mbps we could improve :-)
Tomorrow I'll start digging on it as well, maybe we might join work in
the near future ;-)
Good luck! :-D
[1] http://lxr.linux.no/linux/drivers/usb/core/driver.c#L736
--
Best Regards,
Felipe Balbi
http://felipebalbi.com
me@felipebalbi.com