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hw: Implement timekeeping #30

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mato opened this issue Jun 15, 2015 · 2 comments
Closed

hw: Implement timekeeping #30

mato opened this issue Jun 15, 2015 · 2 comments
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mato commented Jun 15, 2015

As reported by @talex5 while testing mirage-console on rumprun:

I also tested mirage-skeleton/console, which worked but ran rather fast (it's supposed to wait 1s between each print). Calling gettimeofday showed the clock running fast for some reason.

@anttikantee notes:

That's because when I wrote the platform, I didn't bother writing a clock driver, and just used "rtdsc" as an approximation.
@mato mato added the bug label Jun 15, 2015
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Well, hw clock can run slow too, depending on the speed of the CPU ;-)

The code is in platform/hw/arch/{i386,amd64}/machdep.c::bmk_cpu_clock_now()
(if someone looks at this at a later date, both have probably migrated to arch/x86)

mato added a commit that referenced this issue Jun 30, 2015
@mato
hw: Calibrate TSC and correctly scale monotonic time
6faddda 
This is the first phase of addressing issue #30. We calibrate the TSC at
boot against the i8254 timer and calculate a scaleing factor for
monotonic time.
mato added a commit that referenced this issue Jul 3, 2015
@mato
hw: Calibrate TSC and correctly scale monotonic time
b0406eb 
This is the first phase of addressing issue #30. We calibrate the TSC at
boot against the i8254 timer and calculate a scaleing factor for
monotonic time.
@mato mato changed the title hw: Clock runs fast hw: Implement timekeeping Jul 3, 2015
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mato commented Jul 3, 2015

Fixes for this have now been changed to master. Please test, and file issues for any problems encountered. See also full discussion at http://www.freelists.org/post/rumpkernel-users/Implement-timekeeping-for-rumprunhw-x86.

@mato mato closed this as completed Jul 3, 2015
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