On Wed, 8 Sep 2010, Peter Zijlstra wrote: > On Wed, 2010-09-08 at 14:29 +0200, Jan Blunck wrote: > > This patch is disabling the scheduler tick to go off when there is a task > > with SCHED_FIFO policy running. Since these tasks are not timesliced anyway > > we only care about timers, softirqs and such stuff just like when we disable > > the tick during idle periods. > > > > Also, doesn't this break any and all jiffies users? Only on UP. On SMP we hand off the do_timer duty to some other core. > And you need to restart the tick on call_rcu() and everything else that > requires the tick for processing. Not only this. If the task enqueues a timer_list timer via a syscall or an interrupt/softirq enqueues a timer_list timer while the tick is off then this timer will not fire until the task goes back into schedule. That approach is way too naive. There is a boatload of subtle wreckage waiting and it needs careful analysis of this to work. Frederic is looking into this already. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
