On Thu, Sep 27, 2012 at 02:02:05PM +0200, Ivo Sieben 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> Note, I took out the WARN_ON() in this patch, as what is that really going to help here? It also will conflict with a patch from Jiri I'll ba applying after this one, so if you think it's needed, care to send a follow-on patch based on linux-next in a few days? 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
