On 07/23/2015 12:42 PM, Frederic Weisbecker wrote:
+static void cpu_timer_list_dequeue(struct cpu_timer_list *t) +{ + if (!list_empty(&t->entry)) + cpu_timer_dec_tick_dependency(); + list_del_init(&t->entry); +}
Is the list_empty() test necessary? It wasn't in the original posix-timers code, and it feels like a pretty serious bug if you're doing a list_del on an empty list.
At a higher level, is the posix-cpu-timers code here really providing the right semantics? It seems like before, the code was checking a struct task-specific state, and now you are setting a global state such that if ANY task anywhere in the system (even on housekeeping cores) has a pending posix cpu timer, then nothing can go into nohz_full mode.
Perhaps what is needed is a task_struct->tick_dependency to go along with the system-wide and per-cpu flag words?
-- Chris Metcalf, EZChip Semiconductor http://www.ezchip.com -- 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/