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Subject[PATCH] Revert "cpufreq: governor: Fix negative idle_time when configured with CONFIG_HZ_PERIODIC"
Date
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Revert commit 0df35026c6a5 (cpufreq: governor: Fix negative idle_time
when configured with CONFIG_HZ_PERIODIC) that introduced a regression
by causing the ondemand cpufreq governor to misbehave for
CONFIG_TICK_CPU_ACCOUNTING unset (the frequency goes up to the max at
one point and stays there indefinitely).

The revert takes subsequent modifications of the code in question into
account.

Fixes: 0df35026c6a5 (cpufreq: governor: Fix negative idle_time when configured with CONFIG_HZ_PERIODIC)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=115261
Reported-and-tested-by: Timo Valtoaho <timo.valtoaho@gmail.com>
Cc: 4.5+ <stable@vger.kernel.org> # 4.5+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/cpufreq/cpufreq_governor.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

Index: linux-pm/drivers/cpufreq/cpufreq_governor.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/cpufreq_governor.c
+++ linux-pm/drivers/cpufreq/cpufreq_governor.c
@@ -146,12 +146,8 @@ unsigned int dbs_update(struct cpufreq_p
wall_time = cur_wall_time - j_cdbs->prev_cpu_wall;
j_cdbs->prev_cpu_wall = cur_wall_time;

- if (cur_idle_time <= j_cdbs->prev_cpu_idle) {
- idle_time = 0;
- } else {
- idle_time = cur_idle_time - j_cdbs->prev_cpu_idle;
- j_cdbs->prev_cpu_idle = cur_idle_time;
- }
+ idle_time = cur_idle_time - j_cdbs->prev_cpu_idle;
+ j_cdbs->prev_cpu_idle = cur_idle_time;

if (ignore_nice) {
u64 cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
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