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Re: Build time measurements
On Thu, Mar 26, 2020 at 08:44:13PM +0000, Andrew Doran wrote:
> It's a software problem right now. The ACPI idle loop doesn't currenly
> enter a low power sleep state because there are issues with interrupts to
> solve first. Nevertheless it's very heavy on I/O port access, takes locks
> and under certain conditions flushes the entire L1/L2/L3 cache (I haven't
> verified that yet but the cache miss rate observed with tprof(8) is very
None of above is really true. Well, true, it takes a lock, but I doubt
whether locking explains the numbers you are seeing.
Because C3 states are not currently used, the other things do not happen.
Flushing the caches (when entering/leaving C3) happens only with old CPUs,
which certainly is not the case with these benchmarks. The same goes with
To gain more insights, I'd just commment out acpi_cpu::acpicpu_cstate_attach.
It could be, for instance, that you are getting interrupts because of
thermal issues (a.k.a. T-states), which, in turn, is a sign that you
shouldn't be hitting your CPU so hard.
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