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From: Peter Zijlstra on 17 Jun 2010 12:10
Chris Wedgwood reports that 39c0cbe (sched: Rate-limit nohz) causes a
serial console regression, unresponsiveness, and indeed it does. The
below fixes it by not skipping out when the tick has been stopped.

Reported-by: Chris Wedgwood <cw(a)f00f.org>
Tested-by: Brian Bloniarz <bmb(a)athenacr.com>
Signed-off-by: Mike Galbraith <efault(a)gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra(a)chello.nl>
---
kernel/time/tick-sched.c | 5 +----
1 files changed, 1 insertions(+), 4 deletions(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 5f171f0..e0707ea 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -315,9 +315,6 @@ void tick_nohz_stop_sched_tick(int inidle)
goto end;
}

- if (nohz_ratelimit(cpu))
- goto end;
-
ts->idle_calls++;
/* Read jiffies and the time when jiffies were updated last */
do {
@@ -328,7 +325,7 @@ void tick_nohz_stop_sched_tick(int inidle)
} while (read_seqretry(&xtime_lock, seq));

if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) ||
- arch_needs_cpu(cpu)) {
+ arch_needs_cpu(cpu) || nohz_ratelimit(cpu)) {
next_jiffies = last_jiffies + 1;
delta_jiffies = 1;
} else {

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Prev: tracing, function graph: Remove the noisy output when use function graph filter
Next: ACPI / PM: Do not enable GPEs for system wakeup in advance