Am Donnerstag, 16. Januar 2003 01:05 schrieb Greg KH:
> On Thu, Jan 16, 2003 at 12:34:36AM +0100, Oliver Neukum wrote:
> > Hi,
> >
> > I'd like to propose a small further patch.
> >
> > I want to bind URBs to usb_devices at allocation.
> > usb_alloc_urb (int i, int mem_flags) ->
> > usb_alloc_urb (struct usb_device *dev, int i, int mem_flags)
> > and usb_fill_* loose the struct usb_device references.
> >
> > Explanation:
> > The HCDs allocate and deallocate data structures during every submission.
> > This is wasteful, but as long as an URB can be sent to several devices,
> > it is unavoidable, because the devices may be be on busses controlled by
> > different HCDs.
>
> So you would do the allocation at usb_alloc_urb() time instead? Do you
Yes. If the HCD provides a hook. Else we do it as we do know and profit
only from a few cycles as usb_fill_* become faster.
> have any statistics that show the current implementation is actually
> slowing anything down?
No. Does that mean you are volunteering to get me a USB2.0 storage device?
Obviously there will be speed improvement in any case for any driver that
doesn't use an URB pool common to all devices. I can't give you figures though.
In addition there are strategic thoughts. Doing this change allows (although
I think that it's 2.7 stuff) us to handle more of disconnect in usbcore.
We can under these condition link all URBs of a device and walk the list
if we detect a disconnect. If a driver allocates all URBs in probe()
,as many do, handling disconnect() becomes as easy as usbcore can make it.
Regards
Oliver
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