On 02/10/2014 11:04 AM, Preeti Murthy wrote:
Hi Daniel,
On Fri, Feb 7, 2014 at 4:40 AM, Daniel Lezcano
<daniel.lezc...@linaro.org> wrote:
The idle_balance modifies the idle_stamp field of the rq, making this
information to be shared across core.c and fair.c. As we can know if the
cpu is going to idle or not with the previous patch, let's encapsulate the
idle_stamp information in core.c by moving it up to the caller. The
idle_balance function returns true in case a balancing occured and the cpu
won't be idle, false if no balance happened and the cpu is going idle.
Cc: mi...@kernel.org
Cc: alex....@linaro.org
Cc: pet...@infradead.org
Signed-off-by: Daniel Lezcano <daniel.lezc...@linaro.org>
Signed-off-by: Peter Zijlstra <pet...@infradead.org>
---
kernel/sched/core.c | 13 +++++++++++--
kernel/sched/fair.c | 14 ++++++--------
kernel/sched/sched.h | 8 +-------
3 files changed, 18 insertions(+), 17 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 16b97dd..428ee4c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2704,8 +2704,17 @@ need_resched:
pre_schedule(rq, prev);
- if (unlikely(!rq->nr_running))
- idle_balance(rq);
+#ifdef CONFIG_SMP
+ if (unlikely(!rq->nr_running)) {
+ /*
+ * We must set idle_stamp _before_ calling idle_balance(), such
+ * that we measure the duration of idle_balance() as idle time.
Should not this be "such that we *do not* measure the duration of idle_balance()
as idle time?"
Actually, the initial code was including the idle balance time
processing in the idle stamp. When I moved the idle stamp in core.c,
idle balance was no longer measured (an unwanted change). That has been
fixed and to prevent that to occur again, we added a comment.
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