powerd adaptive mode latching

Andrew Atrens atrens at nortel.com
Thu Nov 8 14:55:05 PST 2007


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Simon Barner wrote:
>>> Please see kern/114722. The patch from the PR works fine with my
>>> T61 (T7300).
>>>
>>> Funny enough, I contacted re@ to get this into 7.0 only two minutes ago.
>>>
>>> For the archives, the similar bug described in bin/117375 already seems
>>> to be adressed in RELENG_7.
>> both pr's are open .. and
>>
>> releng_7 and head are both at v 1.26 of acpi_perf.c
>>
>> so, no it's not fixed, *anywhere*.  :)
> 
> It's true that both PRs are still open, but:
> 
> 1) kern/114722 should fix your problem (CPUFREQ_CMP takes care of almost
>    identical frequencies). Have you already had a chance to verify that?
> 
> 2) bin/117375 talks about exactly identical frequencies, which should be
>    handled by acpi_perf.c (1.26, line 303-306). However, the reporter
>    (Cc'ed) of that PR runs FreeBSD 6.2-p8 which already contains the
>    removal of duplicate entries (MFC from acpi_perf.c 1.24).

Well both head and releng7 are using 1.26 and the fix is not there. it's as
simple as that. Just re-read the patch specified in 114722 and then take look at
http://fxr.watson.org/fxr/source/dev/acpica/acpi_perf.c

the issue is that the frequencies aren't identical - it's that they are *nearly* identical.

here's the CPUFREQ_CMP macro -

/usr/include/sys/cpu.h:#define CPUFREQ_CMP(x, y)        (abs((x) - (y)) < 25)

as you can see the macro is dead simple - it just considers any two frequencies within 25Hz
of each other to be identical. in fact when you look at it, and look at my powerd.c patch
both are doing the same thing, except that one is doing it in the kernel, the other in user
space.

I actually like 114722. :)  Someone should commit it!!! :) :) :)

- --Andrew
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