On 10-03-16 11:17, Nathan Rossi wrote:
On Thu, Mar 10, 2016 at 7:29 PM, Mike Looijmans <[email protected]> wrote:
After migrating to the current 4.4 kernel, I noticed that the internal timer
no longer works correctly.
When the CPU frequency scaling sets the CPU speed to 333MHz, the "wall
clock" time also slows down to half the normal rate (e.g. a "sleep 1" will
actually take 2 seconds).
This wasn't the case on the 4.0 kernels.
Is this only on linux-xlnx kernels? or linux-yocto and or mainline kernels too?
It's quite easy to test on ANY kernel, just set the CPU to 333MHz, typically:
echo 333333 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed
and then check how long "sleep 1" really takes.
(Most boards default to "userspace" governor, setting the governor to
"ondemand" will also reduce the speed)
Kind regards,
Mike Looijmans
System Expert
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