* Sebastian Andrzej Siewior <[email protected]> wrote:
> On 2017-04-05 09:39:43 [+0200], Ingo Molnar wrote:
> >
> > So maybe we could add the following facility:
> >
> > ptr = sched_migrate_to_cpu_save(cpu);
> >
> > ...
> >
> > sched_migrate_to_cpu_restore(ptr);
BTW., and I'm sure this has come up before, but why doesn't migrate_disable()
use
a simple per task flag that the scheduler migration code takes into account?
It should be functionally equivalent to the current solution, and it appears to
have a heck of a smaller cross section with the rest of the scheduler.
I.e.:
static inline void migrate_disable(void)
{
current->migration_disabled++;
}
...
static inline void migrate_enable(void)
{
current->migration_disabled--;
}
or so? Then add this flag as a condition to can_migrate_task() et al.
While we generally dislike such flags as they wreck havoc with the scheduler if
overused, the cpus_allowed based solution has the exact same effect so it's not
like it's a step backwards - and it should also be much faster and less
intrusive.
Am I missing some complication?
Thanks,
Ingo
