Re: patch to shift memory allocations to usb_alloc_urb()
Oliver Neukum <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
Am Donnerstag, 5. Juli 2007 schrieb Matthew Dharm: > 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. Yes, we can. 1. How high is the price? 2. Is it worth it? 3. Isn't a version using one backup URB better? Regards Oliver ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel