On Thu, Sep 27, 2012 at 02:15:22PM +0100, Alan Cox wrote: > On Thu, 27 Sep 2012 13:58:21 +0200 > Ivo Sieben <meltedpianoman@xxxxxxxxx> wrote: > > > When low_latency flag is set the TTY receive flip buffer is copied to the > > line discipline directly instead of using a work queue in the background. > > Therefor only in case a workqueue is actually used for copying data to the > > line discipline we'll have to flush the workqueue. > > > > This prevents unnecessary spin lock/unlock on the workqueue spin lock that > > can cause additional scheduling overhead on a PREEMPT_RT system. On a 200 > > MHz AT91SAM9261 processor setup this fixes about 100us of scheduling > > overhead on the TTY read call. > > > > Signed-off-by: Ivo Sieben <meltedpianoman@xxxxxxxxx> > > Acked-by: Alan Cox <alan@xxxxxxxxxxxxxxx> > > (but for 3.8 not 3.7 ...) Yes, I will hold onto this until 3.7-rc1 is out, thanks. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
