Re: Information about move_tasks return

From: Darren Hart
Date: Mon Nov 22 2004 - 23:50:11 EST


On Mon, 2004-11-22 at 08:16 -0400, Cícero wrote:
> hi
>
> I am looking for the result of the function move_task in
>
> kernel/sched.c , I have observed that it returns an int value and as I
> print it with printk.
>
> I have created a int variable 'results_move_task' which capture the result of
>
> move_task and I print it with printk("%d",results_move_task); I
> observed that it often returns the value '1' and sometimes it returns
> '2' or more. Is it really correct?

/*
* move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
* as part of a balancing operation within "domain". Returns the number of
* tasks moved.
*
* Called with both runqueues locked.
*/
static int move_tasks(runqueue_t *this_rq, int this_cpu, runqueue_t *busiest,
unsigned long max_nr_move, struct sched_domain *sd,
enum idle_type idle)
{
...


So as the "documentation" states, it returns the number of tasks
actually moved. For instance, The balancing code may request 4 tasks be
moved, but for various reasons, only 2 were actually moved to other
CPUs, move_tasks() would return 2.

--
Darren Hart <darren@xxxxxxxxxx>

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