On 12/04/17 17:32, Peter Zijlstra wrote:
On Wed, Apr 12, 2017 at 04:40:11PM +0300, Martin Peres wrote:
So, why is this only affecting the Core 2 Duo?
Core2 doesn't have a usable TSC and would revert to the slow path. I'll
have another look at that patch.
So, by default, it is using the hpet clock source. FYI, I tried the only
other available clock source (acpi_pm) and got the same result.
So because HPET is unbearably slow we've cobbled together something that
takes the HPET (or rather get-time-of-day CLOCK_MONOTONIC) value at tick
time and uses TSC to add per-cpu increments to that. Using windowing to
keep the TSC maddness at bay.
The patch in question affects the windowing.. clearly something went
amiss.
Good to know. Is there a way to disable this behaviour, as a workaround
for our CI system until a proper fix lands? We already pushed locally
the revert for this patch, but that may affect other platforms which do
not exhibit the problem.
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