Another interesting thing, enabling usbmon will increase performance a lot.
root@tom-panda:~# dd if=/dev/sda iflag=direct of=/dev/null bs=128K count=32 32+0 records in 32+0 records out 4194304 bytes (4.2 MB) copied, 3.4598 s, 1.2 MB/s root@tom-panda:~# cat /sys/kernel/debug/usb/usbmon/1u > /tmp/usbmon-1u& [1] 1485 root@tom-panda:~# dd if=/dev/sda iflag=direct of=/dev/null bs=128K count=32 32+0 records in 32+0 records out 4194304 bytes (4.2 MB) copied, 0.795455 s, 5.3 MB/s root@tom-panda:~# dd if=/dev/sda iflag=direct of=/dev/null bs=128K count=32 32+0 records in 32+0 records out 4194304 bytes (4.2 MB) copied, 0.278628 s, 15.1 MB/s root@tom-panda:~# killall -9 cat [1]+ Killed cat /sys/kernel/debug/usb/usbmon/1u > /tmp/usbmon-1u root@tom-panda:~# dd if=/dev/sda iflag=direct of=/dev/null bs=128K count=32 32+0 records in 32+0 records out 4194304 bytes (4.2 MB) copied, 5.0556 s, 830 kB/s root@tom-panda:~# dd if=/dev/sda iflag=direct of=/dev/null bs=128K count=32 32+0 records in 32+0 records out 4194304 bytes (4.2 MB) copied, 3.2009 s, 1.3 MB/s -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/709245 Title: panda: USB disk IO slow To manage notifications about this bug go to: https://bugs.launchpad.net/linaro-ubuntu/+bug/709245/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
