Hi, A while back I did some initial attempts at unifying the single-urb fifo-based and the multi-urb dynamically-allocated urb write implementations, but although the performance results were promising my design at the time was a bit too complex. I decided to postpone this and instead turn ftdi_sio into a kfifo-based generic driver first, but I soon realised that a single urb would not suffice to achieve maximum throughput. So I kept both schemes to avoid any regressions and instead made the prepare_write_buffer interface fit them both. Today I thought some more about the unification and came up with a new design that is both simple and clean, and that not only achieves maximum throughput but also does so at significantly lower CPU-usage for small writes (and only slightly higher for 2k ones). It currently uses two pre-allocated urbs (and buffers) so in contrast to the current multi-urb writes it does no allocations during runtime and also puts less pressure on the host-stack queues. This also simplifies the prepare_write_buffer interface. These patches apply on top of the series I posted yesterday, and with them included the diff-stat for the whole series is: drivers/usb/serial/aircable.c | 499 ++++----------------------------------- drivers/usb/serial/cp210x.c | 16 +- drivers/usb/serial/ftdi_sio.c | 388 ++++--------------------------- drivers/usb/serial/generic.c | 304 +++++++----------------- drivers/usb/serial/pl2303.c | 421 ++------------------------------ drivers/usb/serial/usb-serial.c | 36 +++- drivers/usb/serial/usb_debug.c | 4 +- include/linux/usb/serial.h | 25 ++- 8 files changed, 260 insertions(+), 1433 deletions(-) Thanks, Johan Johan Hovold (2): USB: serial: reimplement generic fifo-based writes USB: serial: remove multi-urb write from generic driver drivers/usb/serial/aircable.c | 9 +- drivers/usb/serial/ftdi_sio.c | 57 ++++-------- drivers/usb/serial/generic.c | 192 +++++++++++---------------------------- drivers/usb/serial/usb-serial.c | 34 +++++++- include/linux/usb/serial.h | 16 ++- 5 files changed, 121 insertions(+), 187 deletions(-) -- 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
