From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932098AbXJSSsX (ORCPT ); Fri, 19 Oct 2007 14:48:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S935343AbXJSSob (ORCPT ); Fri, 19 Oct 2007 14:44:31 -0400 Received: from ms-smtp-03.nyroc.rr.com ([24.24.2.57]:55505 "EHLO ms-smtp-03.nyroc.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933590AbXJSSoZ (ORCPT ); Fri, 19 Oct 2007 14:44:25 -0400 Message-Id: <20071019184337.305006472@goodmis.org> References: <20071019184254.456160632@goodmis.org> User-Agent: quilt/0.46-1 Date: Fri, 19 Oct 2007 14:43:02 -0400 From: Steven Rostedt To: LKML , RT Cc: Linus Torvalds , Andrew Morton , Ingo Molnar , Thomas Gleixner , Gregory Haskins , Peter Zijlstra Subject: [patch 8/8] disable CFS RT load balancing. Content-Disposition: inline; filename=disable-CFS-rt-balance.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Since we now take an active approach to load balancing, we don't need to balance RT tasks via CFS. In fact, this code was found to pull RT tasks away from CPUS that the active movement performed, resulting in large latencies. Signed-off-by: Steven Rostedt --- kernel/sched_rt.c | 90 +----------------------------------------------------- 1 file changed, 2 insertions(+), 88 deletions(-) Index: linux-test.git/kernel/sched_rt.c =================================================================== --- linux-test.git.orig/kernel/sched_rt.c 2007-10-19 12:36:07.000000000 -0400 +++ linux-test.git/kernel/sched_rt.c 2007-10-19 13:01:31.000000000 -0400 @@ -535,100 +535,14 @@ static void put_prev_task_rt(struct rq * p->se.exec_start = 0; } -/* - * Load-balancing iterator. Note: while the runqueue stays locked - * during the whole iteration, the current task might be - * dequeued so the iterator has to be dequeue-safe. Here we - * achieve that by always pre-iterating before returning - * the current task: - */ -static struct task_struct *load_balance_start_rt(void *arg) -{ - struct rq *rq = arg; - struct rt_prio_array *array = &rq->rt.active; - struct list_head *head, *curr; - struct task_struct *p; - int idx; - - idx = sched_find_first_bit(array->bitmap); - if (idx >= MAX_RT_PRIO) - return NULL; - - head = array->queue + idx; - curr = head->prev; - - p = list_entry(curr, struct task_struct, run_list); - - curr = curr->prev; - - rq->rt.rt_load_balance_idx = idx; - rq->rt.rt_load_balance_head = head; - rq->rt.rt_load_balance_curr = curr; - - return p; -} - -static struct task_struct *load_balance_next_rt(void *arg) -{ - struct rq *rq = arg; - struct rt_prio_array *array = &rq->rt.active; - struct list_head *head, *curr; - struct task_struct *p; - int idx; - - idx = rq->rt.rt_load_balance_idx; - head = rq->rt.rt_load_balance_head; - curr = rq->rt.rt_load_balance_curr; - - /* - * If we arrived back to the head again then - * iterate to the next queue (if any): - */ - if (unlikely(head == curr)) { - int next_idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1); - - if (next_idx >= MAX_RT_PRIO) - return NULL; - - idx = next_idx; - head = array->queue + idx; - curr = head->prev; - - rq->rt.rt_load_balance_idx = idx; - rq->rt.rt_load_balance_head = head; - } - - p = list_entry(curr, struct task_struct, run_list); - - curr = curr->prev; - - rq->rt.rt_load_balance_curr = curr; - - return p; -} - static unsigned long load_balance_rt(struct rq *this_rq, int this_cpu, struct rq *busiest, unsigned long max_nr_move, unsigned long max_load_move, struct sched_domain *sd, enum cpu_idle_type idle, int *all_pinned, int *this_best_prio) { - int nr_moved; - struct rq_iterator rt_rq_iterator; - unsigned long load_moved; - - rt_rq_iterator.start = load_balance_start_rt; - rt_rq_iterator.next = load_balance_next_rt; - /* pass 'busiest' rq argument into - * load_balance_[start|next]_rt iterators - */ - rt_rq_iterator.arg = busiest; - - nr_moved = balance_tasks(this_rq, this_cpu, busiest, max_nr_move, - max_load_move, sd, idle, all_pinned, &load_moved, - this_best_prio, &rt_rq_iterator); - - return load_moved; + /* don't touch RT tasks */ + return 0; } static void task_tick_rt(struct rq *rq, struct task_struct *p) --