From mboxrd@z Thu Jan  1 00:00:00 1970
From: bugzilla-daemon@bugzilla.kernel.org
Subject: [Bug 69821] setting CONFIG_HZ_PERIODIC locks cpu at the lowest
 frequency using ONDEMAND
Date: Tue, 15 Dec 2015 00:12:02 +0000
Message-ID: <bug-69821-12968-3QWufT2Out@https.bugzilla.kernel.org/>
References: <bug-69821-12968@https.bugzilla.kernel.org/>
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https://bugzilla.kernel.org/show_bug.cgi?id=69821

--- Comment #4 from Chen Yu <yu.c.chen@intel.com> ---
CONFIG_NO_HZ_FULL  is using ktime_get to get the idle time in
get_cpu_idle_time_us, it is based on clock source,  while if the kernel config
is set with CONFIG_HZ_PERIODIC , the governor might get idle time by
jiffies(tick, minimum unit of 4 millisecond),
the former is more accurate than the latter, this might be one of the reason
for the problem. I can try to reproduce and take a look.

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