Dear all,
I have written a simple bulkusb driver to test the usb transfer speed. Just
transfer 256bytes*1000 between host and client. The test result is following:
transfer data transfer speed
host--->client 256bytes*1000 256K bytes/second
client--->host 256bytes*1000 62K bytes/second
I'm very confused of this transfer speed(client--->host) result. From the usb
analyzer snap data, the time is almost spent on "Waitting for next IN Token".
My bulkusb codes is the following:
...
bulkusb_probe()
{...
/*Build a read urb and send a IN token first time*/
FILL_BULK_URB(&bulkusb->readurb, usbdev, usb_rcvbulkpipe(usbdev,
bulkusb->bulk_in_ep),
bulkusb->ibuf, readsize, bulkusb_readback, bulkusb);
bulkusb->readurb.transfer_flags |= USB_ASYNC_UNLINK;
/*send a IN token first time*/
bulkusb->readurb.dev = bulkusb->bulkusb_dev;
if(usb_submit_urb(&bulkusb->readurb))
{
printk("bulkusb_probe: usb_submit_urb(read) failed!\n");
}
...
}
bulkusb_readback(struct urb *urb)
{...
urb->actual_length = 0;
urb->dev = bulkusb->bulkusb_dev;
if (usb_submit_urb(urb))
{
printk("failed resubmitting read urb\n");
}
...
}
Usb analyzer snap data:
<<...OLE_Obj...>>
Could anybodies help me analyze or give me some advice? Thanks a lot!
Regards,
Levis xu
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