On 03/04, Arun R Bharadwaj wrote:
>
> @@ -628,7 +629,7 @@ __mod_timer(struct timer_list *timer, un
> {
> struct tvec_base *base, *new_base;
> unsigned long flags;
> - int ret;
> + int ret, current_cpu, preferred_cpu;
>
> ret = 0;
>
> @@ -649,6 +650,16 @@ __mod_timer(struct timer_list *timer, un
>
> new_base = __get_cpu_var(tvec_bases);
>
> + current_cpu = smp_processor_id();
> + preferred_cpu = get_nohz_load_balancer();
> + if (enable_timer_migration && !tbase_get_pinned(timer->base) &&
> + idle_cpu(current_cpu) && preferred_cpu != -1) {
> + new_base = per_cpu(tvec_bases, preferred_cpu);
> + timer_set_base(timer, new_base);
> + timer->expires = expires;
> + internal_add_timer(new_base, timer);
> + goto out_unlock;
I didn't read the whole series, but this looks very wrong.
We can not do internal_add_timer/etc until we lock new_base, please
look how the current code does this under "if (base != new_base)".
I think you can do something like
- new_base = __get_cpu_var(tvec_bases);
+
+ new_cpu = smp_processor_id();
+ if (enable_timer_migration && ....)
+ new_cpu = preferred_cpu;
+
+ new_base = per_cpu(tvec_bases, new_cpu);
if (base != new_base) {
Oleg.
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