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由 Ming Lei 提交于
The link change is detected via the interrupt pipe, and bulk pipes are responsible for transfering packets, so it is reasonable to stop bulk transfer after link is reported as off. Two adavantages may be obtained with stopping bulk transfer after link becomes off: - USB bus bandwidth is saved(USB bus is shared bus except for USB3.0), for example, lots of 'IN' token packets and 'NYET' handshake packets is transfered on 2.0 bus. - probabaly power might be saved for usb host controller since cancelling bulk transfer may disable the asynchronous schedule of host controller. With this patch, when link becomes off, about ~10% performance boost can be found on bulk transfer of anther usb device which is attached to same bus with the usbnet device, see below test on next-20130410: - read from usb mass storage(Sandisk Extreme USB 3.0) on pandaboard with below command after unplugging ethernet cable: dd if=/dev/sda iflag=direct of=/dev/null bs=1M count=800 - without the patch 1, 838860800 bytes (839 MB) copied, 36.2216 s, 23.2 MB/s 2, 838860800 bytes (839 MB) copied, 35.8368 s, 23.4 MB/s 3, 838860800 bytes (839 MB) copied, 35.823 s, 23.4 MB/s 4, 838860800 bytes (839 MB) copied, 35.937 s, 23.3 MB/s 5, 838860800 bytes (839 MB) copied, 35.7365 s, 23.5 MB/s average: 23.6MB/s - with the patch 1, 838860800 bytes (839 MB) copied, 32.3817 s, 25.9 MB/s 2, 838860800 bytes (839 MB) copied, 31.7389 s, 26.4 MB/s 3, 838860800 bytes (839 MB) copied, 32.438 s, 25.9 MB/s 4, 838860800 bytes (839 MB) copied, 32.5492 s, 25.8 MB/s 5, 838860800 bytes (839 MB) copied, 31.6178 s, 26.5 MB/s average: 26.1MB/s Signed-off-by: NMing Lei <ming.lei@canonical.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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