Commit-ID:  bbf18b19495942cc730e8ff11fc3ffadf20cbfe1
Gitweb:     http://git.kernel.org/tip/bbf18b19495942cc730e8ff11fc3ffadf20cbfe1
Author:     Prashanth Nageshappa <[email protected]>
AuthorDate: Tue, 19 Jun 2012 17:52:07 +0530
Committer:  Ingo Molnar <[email protected]>
CommitDate: Tue, 24 Jul 2012 13:55:37 +0200

sched: Reset loop counters if all tasks are pinned and we need to redo load 
balance

While load balancing, if all tasks on the source runqueue are pinned,
we retry after excluding the corresponding source cpu. However, loop counters
env.loop and env.loop_break are not reset before retrying, which can lead
to failure in moving the tasks. In this patch we reset env.loop and
env.loop_break to their inital values before we retry.

Signed-off-by: Prashanth Nageshappa <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 kernel/sched/fair.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9361669..f9f9aa0 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4288,8 +4288,11 @@ more_balance:
                /* All tasks on this runqueue were pinned by CPU affinity */
                if (unlikely(env.flags & LBF_ALL_PINNED)) {
                        cpumask_clear_cpu(cpu_of(busiest), cpus);
-                       if (!cpumask_empty(cpus))
+                       if (!cpumask_empty(cpus)) {
+                               env.loop = 0;
+                               env.loop_break = sched_nr_migrate_break;
                                goto redo;
+                       }
                        goto out_balanced;
                }
        }
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