Re: patch to shift memory allocations to usb_alloc_urb()

On Mon, Jul 02, 2007 at 09:15:03AM +0200, Oliver Neukum wrote:
> Am Montag, 2. Juli 2007 schrieb Alan Stern:
> > If you look at usbmon logs of real usb-storage data transfers you'll
> > see that multi-page sg elements occur quite frequently.  (Of course,
> > that doesn't prevent us from transferring only one page per URB.)
> 
> OK, but the storage driver allocates the URBs on the fly. If we change
> that to preallocation we need to have enough URBs for the worst case.

Of course, in the storage case we control the worst-case.  By adjusting the
parameter which controls how long a sg list the SCSI core will send us, we
can effectively limit the worst-case number of URBs needed.

Matt

-- 
Matthew Dharm                              Home: [email protected] 
Maintainer, Linux USB Mass Storage Driver

I want my GPFs!!!
					-- Stef
User Friendly, 11/9/1998

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