On Sun, Sep 29, 2013 at 9:01 PM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > On Sun, Sep 29, 2013 at 07:32:56PM +0200, Markus Rechberger wrote: >> On Sun, Sep 29, 2013 at 5:14 PM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: >> > On Sun, Sep 29, 2013 at 04:02:56PM +0200, Markus Rechberger wrote: >> >> This patch adds memory mapping support to USBFS for isochronous and bulk >> >> data transfers, it allows to pre-allocate usb transfer buffers. >> >> >> >> The CPU usage decreases 1-2% on my 1.3ghz U7300 notebook >> >> The CPU usage decreases 6-8% on an Intel Atom n270 when >> >> transferring 20mbyte/sec (isochronous), it should be more interesting to >> >> see those >> >> statistics on embedded systems where copying data is more expensive. >> > >> > Do you have a userspace test program that we can use to verify that this >> > does work, and that others can use to run on some different platforms to >> > verify that this is actually faster? >> > >> >> You will need one of our devices for testing I guess. Some scanners >> (which use USBFS) or other low speed devices won't really utilize >> usbfs too much. I think I could provide some grabber device for >> testing if you want to. > > So no test userspace program you can knock up for us? I really hate > adding new core functionality to the kernel that I have no way of > testing at all, that's a recipe for it quickly breaking... > Well do you have any device which has a userspace driver? Without a device you can barely test it. There's a settopbox company which added the backported patch to Linux 3.2 they use USB cardreaders and even tested the devices with and without mmap support. I doubt that the SG support has any good testing on low end systems, I'm worried that it will introduce those latency issues again which we saw with 15k buffers. 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
