On Thu, Sep 26, 2013 at 5:17 AM, Markus Rechberger <mrechberger@xxxxxxxxx> wrote: > On Thu, Sep 26, 2013 at 2:13 AM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: >> On Tue, Sep 24, 2013 at 09:12:39PM +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. >> >> Does libusb support this? >> > > not yet, we're directly accessing usbfs with our userspace usb driver. > It should be easy for libusb devs to pick up that extension. > > The devices are USB video devices. > http://sundtek.de/support/toggo2.mpg (captured from our usb device) > http://sundtek.de/images/mc_st_640.jpg > >>> The CPU usage decreases 1-2% on my 1.3ghz U7300 notebook when >>> transferring 20mbyte/sec, it should be more interesting to see those >>> statistics on embedded systems where copying data is more expensive. >> >> Any chance you could test this on a system with a "smaller" processor to >> see if that really is the case or not? >> > > I'm also curious about that, unfortunately I don't have any time for > that at the moment. > We support some embedded systems where copying data is very expensive, > that's what that patch has been written for. If this patch would enter > the kernel now it would probably take one year or longer to get picked > up by those systems. > > http://sundtek.de/support/devio_wo_mmap.mts > http://sundtek.de/support/devio_mmap.mts > > both tests are using the same kernel, the wo_mmap file is using the > legacy mode, it sticks between 8-10% (even 12%) CPU usage, while the > other one sticks between 6-8% (max 10%). > At the time writing this email the files are still uploading, so you > might wait another hour before downloading them. > it is copying ~20 MByte/sec (Isochronous) 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
