Hi Frederic, > /* > @@ -1279,6 +1277,7 @@ void run_posix_cpu_timers(struct task_struct *tsk) > LIST_HEAD(firing); > struct k_itimer *timer, *next; > unsigned long flags; > + struct signal_struct *sig; > > BUG_ON(!irqs_disabled()); > > @@ -1336,6 +1335,10 @@ void run_posix_cpu_timers(struct task_struct *tsk) > cpu_timer_fire(timer); > spin_unlock(&timer->it_lock); > } > + > + sig = tsk->signal; > + if (task_cputime_zero(&sig->cputime_expires)) > + stop_process_timers(sig); > } > > /* I have proposed a different modification for the same problem yesterday:
https://lkml.org/lkml/2013/4/17/351 I might be mistaken but I believe that firing timers are not rescheduled in the current interrupt context. They are going to be rescheduled later from the task context handling the timer generated signal. Also, if the cputimer is started by posix_cpu_timer_set() without arming any timer, the stop_process_timers() function will never be reached. My methodology to test the modifications that I have proposed is by adding a printk() statement inside thread_group_cputimer() where the cputimer is initialized and run glibc-2.17/rt/tst-cputimer1 unittest. Before the changes, the cputimer is initialized 4 times! I was expecting with the proposed changes to see that number reduced to 2 but it ended up to be even better and be only 1 because the second waves of posix cpu timers is set within 1 tick. If you do the same test with your changes, I think that there is a chance that it will not get the same positive result for the reason that I have stated above. To conclude, I would be very interested to get your input in posix cpu timer modification proposal that I did last week. My proposal is either too complex or I am very bad explaining it so since your knowledgable in the area, your input would be very helpful. https://lkml.org/lkml/2013/4/5/370 Thank you!!! Olivier -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
