• Mike Looijmans's avatar
    usb: gadget: ether: Allow jumbo frames · bba787a8
    Mike Looijmans authored
    USB network adapters support Jumbo frames. The only thing blocking
    that feature is the code in the gadget driver that disposes of
    packets larger than 1518 bytes, and the limit on the ioctl to set
    the mtu.
    
    This patch relaxes these limits, and allows up to 15k frames sizes.
    The 15k value was chosen because 16k does not work on all platforms,
    and usingclose to 16k will result in allocating 5 or 8 4k pages to
    store the skb, wasting pages at no measurable performance gain.
    
    On a topic-miami board (Zynq-7000), iperf3 performance reports:
    MTU= 1500, PC-to-gadget: 139 Mbps, Gadget-to-PC: 116 Mbps
    MTU=15000, PC-to-gadget: 239 Mbps, Gadget-to-PC: 361 Mbps
    
    On boards with slower CPUs the performance improvement will be
    relatively much larger, e.g. an OMAP-L138 increased from 40 to
    220 Mbps using a similar patch on an  2.6.37 kernel.
    Signed-off-by: default avatarMike Looijmans <mike.looijmans@topic.nl>
    Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
    bba787a8
u_ether.c 29 KB