From 157317ba3ec3e5a4d9683b8d24ba40b4f8f3296b Mon Sep 17 00:00:00 2001 From: Zhao Yakui Date: Wed, 2 Jun 2010 11:04:09 +0800 Subject: [PATCH] ACPI: Fix the incorrect calculation about C-state idle time The C-state idle time is not calculated correctly, which will return the wrong residency time in C-state. It will have the following effects: 1. The system can't choose the deeper C-state when it is idle next time. Of course the system power is increased. E.g. On one server machine about 40W idle power is increased. 2. The powertop shows that it will stay in C0 running state about 95% time although the system is idle at most time. 2.6.35-rc1 regression caused-by: 2da513f582a96c053aacc2c92873978d2ea7abff (ACPI: Minor cleanup eliminating redundant PMTIMER_TICKS to NS conversion) Signed-off-by: Zhao Yakui Reported-by: Yu Zhidong Tested-by: Yu Zhidong Acked-by: Venkatesh Pallipadi Signed-off-by: Len Brown --- drivers/acpi/processor_idle.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 2e8c27d..6b38a6b 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -1022,7 +1022,7 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev, spin_unlock(&c3_lock); } kt2 = ktime_get_real(); - idle_time_ns = ktime_to_us(ktime_sub(kt2, kt1)); + idle_time_ns = ktime_to_ns(ktime_sub(kt2, kt1)); idle_time = idle_time_ns; do_div(idle_time, NSEC_PER_USEC); -- 2.7.4