Re: [Patch RT] Fix CFS load balancing for RT tasks
From: Thomas Gleixner <hidden>
Date: 2007-07-11 17:06:36
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On Wed, 2007-07-11 at 16:47 +0200, Sébastien Dugué wrote:
The following patch fixes this by re-enabling the RT overload detection
for the CFS. It may not be the right solution, maybe it should be incorporated
into the other load balancing mechanisms. I did not digg deep enough yet
to make that call ;-)
P.S. Thanks to Steven Rostedt for logdev which is proving invaluable in
cases like this.
Sébastien.Nice catch. That was dropped during the CFS -> -rt merge. tglx
quoted hunk ↗ jump to hunk
------------------ The RT overload mechanism of the O(1) scheduler has not been activated in the new CFS. This patch fixes that by inserting calls to inc_rt_tasks() and dec_rt_tasks() in enqueue_task_rt() and dequeue_task_rt() respectively, which enables the balance_rt_tasks() to be run in the rt_overload case. Signed-off-by: Sébastien Dugué <redacted> --- kernel/sched_rt.c | 4 ++++ 1 file changed, 4 insertions(+) Index: linux-2.6.21.5-rt20/kernel/sched_rt.c ===================================================================--- linux-2.6.21.5-rt20.orig/kernel/sched_rt.c 2007-07-11 10:46:26.000000000 +0200 +++ linux-2.6.21.5-rt20/kernel/sched_rt.c 2007-07-11 10:46:50.000000000 +0200@@ -32,6 +32,8 @@ enqueue_task_rt(struct rq *rq, struct ta list_add_tail(&p->run_list, array->queue + p->prio); __set_bit(p->prio, array->bitmap); + + inc_rt_tasks(p, rq); } /*@@ -44,6 +46,8 @@ dequeue_task_rt(struct rq *rq, struct ta update_curr_rt(rq, now); + dec_rt_tasks(p, rq); + list_del(&p->run_list); if (list_empty(array->queue + p->prio)) __clear_bit(p->prio, array->bitmap);