On Wednesday 16 May 2007, David Brownell wrote: > On Wednesday 16 May 2007, Hans Petter Selasky wrote: > > Hi, > > > > I'm currently working on a Linux USB emulation layer for FreeBSD. In that > > regard I have some issues that makes the stack peform non-optimal due to > > its API design. > > > >... > > > > in that when you have > > pre-allocated all buffers and all USB host controller descriptors, you > > will never get in the situation of not being able to allocate transfer > > descriptors on the fly, like done on Linux. > > That's not a failure mode that's been often observed on Linux. (Never, > in my own experience... which I admit has not focussed on that particular > type of stress load.) So it's hard to argue that it should motivate a > redesign of core APIs.
A user of the Linux UVC driver unfortunately reported such a failure. The driver allocates 5 bulk URBs, and the device asked for a 2.7MB buffer. The system had been used for quite some time, and the user reported that allocating such an amount of contiguous memory made the box swap out and become very slow. Laurent Pinchart ------------------------------------------------------------------------- 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/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
