Hi Lalit... On Wed, Dec 8, 2010 at 13:15, lalit mohan tripathi <lalit.tripathi@xxxxxxxxx> wrote: > Thanks for your reply. The global timer interrupt is called > periodically at the HZ frequency (or as set for per-cpu local timers > in case of SMP). > Can you shed more light about what you mean by "timer interrupt is reenabled"? > In my thinking timer interrupt (single-core: global timer interrupt, > SMP: local timer interrupt) would anyway run at regular interval > (unless preemption is disabled for brief moment). OK, since I am more or less as clueless as you are (can't find any exact code trace so far), so I'd just share my suspicion: As the comment says "this function (scheduler_tick) is also called when parent's time slice is recalculated", I highly suspect that at that "recalculation" stage, timer interrupt is disabled. Thus, scheduler_tick...for few moments is also skipped. Why I guess so? If recalculation happen and at the same time timer interrupt is still "running", quite likely one will disrupt other. The net result: time slice final value isn't as expected. Once the recalculation is done, timer interrupt should be re-enabled. Thus, at this point, scheduler tick...indirectly is also called. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
