On Wed, 10 Jun 2015 07:32:52 -0400, Peter Hurley wrote: > On 06/09/2015 02:05 PM, Steven Walter wrote: > > Use a dedicated kthread for handling ports marked as low_latency. Since > > this thread is RT_FIFO, it is not subject to the same types of > > starvation as the normal priority kworker threads. > > This is not a problem unique to the tty subsystem; many subsystems use > kworkers to handle i/o after the initial ISR. > > Without careful design, high-prio userspace RT threads can effectively starve > themselves of i/o. > > In any event, solutions to this problem belong either in the core workqueue > (for example, an i/o-specific unbounded workqueue) or in the CONFIG_PREEMPT_RT > patch. But kthread_worker *is* the workqueue subsystem's answer to users who require low-latency processing. SPI subsystem has been using it successfully for message pump handling for last few releases. Lack of RT functionality in workqueue subsystem and prevalence of wq use makes them a huge pain on embedded/rt systems. I would like to see more generic solution to this problem as well but I can't think of one :/ -- 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
