On Fri, Aug 19, 2011 at 8:23 AM, Oliver Neukum <oliver@xxxxxxxxxx> wrote: > Am Mittwoch, 17. August 2011, 19:44:16 schrieb Markus Rechberger: >> I understand that USBFS is not 100% optimized, although we are already >> using 3-4 times that much buffer with isochronous and it was working >> fine for years so far as long as the system doesn't run out of memory >> .. but even kerneldrivers would have issues with it in such a >> situation. > > The problem is not what happens on your test system dedicated to this use. > There it'll work. But you allowed everybody else to make the kernel request > the second largest chunk of memory there is. On a otherwise busy system > with fragmented memory this is not good. > > As I said, you want scatter/gather if you need this. > There still would be the problem with the API, but if this is really a problem, > you could define a new ioctl() > let's say there are a few thousand users of the 190k isochronous implementation. I don't want to add more complex code to the kernel, if it's not accepted I'm okay with it, since I know the performance impact I can recommend it to those who are interested in it. Our software works without it anyway, and Bulk is just for special use in our case. Best Regards, Markus -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
