From mboxrd@z Thu Jan 1 00:00:00 1970 From: ville.syrjala@linux.intel.com Subject: [PATCH] Revert "cpuidle: Replace ktime_get() with local_clock()" Date: Thu, 20 Apr 2017 15:44:47 +0300 Message-ID: <20170420124447.13716-1-ville.syrjala@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: Sender: stable-owner@vger.kernel.org To: linux-pm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Daniel Lezcano , Peter Zijlstra , "Rafael J . Wysocki" , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= List-Id: linux-pm@vger.kernel.org From: Ville Syrjälä This reverts commit e93e59ce5b85e6c2b444f09fd1f707274ec066dc. The TSC stops in deeper C states, so using local_clock() in cpuidle to track the C state residency seems like a bad idea. With local_clock() powertop is reporting mostly 0% residency for C states here. Presumably the core is still spending most of its time in some deep C-state since the totals typically add up to only 5% or so, so perhaps the governor isn't getting totally confused by these bogus numbers. But let's go back to using ktime_get() as that at least works correctly across the board. Note that the code has changed somewhat since the regression happened, so this isn't a 1:1 revert of the offending commit. Cc: stable@vger.kernel.org Cc: Daniel Lezcano Cc: Peter Zijlstra (Intel) Cc: Rafael J. Wysocki Signed-off-by: Ville Syrjälä --- drivers/cpuidle/cpuidle.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 548b90be7685..24a52805527f 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -213,13 +213,13 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, sched_idle_set_state(target_state); trace_cpu_idle_rcuidle(index, dev->cpu); - time_start = ns_to_ktime(local_clock()); + time_start = ktime_get(); stop_critical_timings(); entered_state = target_state->enter(dev, drv, index); start_critical_timings(); - time_end = ns_to_ktime(local_clock()); + time_end = ktime_get(); trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); /* The cpu is no longer idle or about to enter idle. */ -- 2.10.2