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Subject[BUG, bisect] hrtimer: severe lag after suspend & resume
all,

After a fresh boot, the Chrome web browser behaves normally. Pages
load quickly and scroll fast. Even image heavy sites such as
images.google.com work fine. However, after a suspend and resume
cycle, Chrome becomes very slow. Pages take ten seconds or more to
load. The scroll bars and buttons are almost completely
unresponsive. Interestingly, I can run Firefox on the same sites
and it has no issue whatsoever.

I have bisected the kernel and found that the following commit
introduced the bug. It is present in the latest linux-next (20150602).

From 868a3e915f7f5eba8f8cb4f7da2276760807c51c Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 14 Apr 2015 21:08:37 +0000
Subject: [PATCH] hrtimer: Make offset update smarter

On every tick/hrtimer interrupt we update the offset variables of the
clock bases. That's silly because these offsets change very seldom.

Add a sequence counter to the time keeping code which keeps track of
the offset updates (clock_was_set()). Have a sequence cache in the
hrtimer cpu bases to evaluate whether the offsets must be updated or
not. This allows us later to avoid pointless cacheline pollution.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20150414203501.132820245@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
---
include/linux/hrtimer.h | 4 ++--
include/linux/timekeeper_internal.h | 2 ++
kernel/time/hrtimer.c | 3 ++-
kernel/time/timekeeping.c | 23 ++++++++++++++++-------
kernel/time/timekeeping.h | 7 ++++---
5 files changed, 26 insertions(+), 13 deletions(-)

--
- Jeremiah Mahler


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