On 08.04.2011 19:53, Daniel Gerzo wrote:
On Fri, 08 Apr 2011 18:02:28 +0300, Alexander Motin wrote:
OK, I understand what you are saying here. On the other side, I know
pretty well how the load is distributed - in this particular case, the
box is a web server, running ~30 php-cgi processes.
This kind of operation doesn't require very high frequency and I suspect
the cores are never waiting for each other. There could be an option
which would allow an administrator to decide whether this is the case
and allow him to set a higher -r and -i values, what do you think?
I think it should be possible with minimal changes.
So, here is my attempt to implement it:
http://danger.rulez.sk/powerd.diff
Can you please review & comment? I should be able to commit it mysqlf if
you consider it acceptable. It seems to work for me :)
Looks fine, except that -f option have to be the first, that is not
obvious. Another moment -- I've noticed some load constants hardcoded
there. They should also be handled to make higher values to work properly.
Any idea what I should look for in the BIOS?
Something about C-states, or Cx-states on the CPU page. But first
look at dev.cpu.X.cx_supported to make sure it is not already present
and just unused.
Seems like it was enabled by default. I have like these:
dev.cpu.0.cx_supported: C1/3 C2/96 C3/128
Does that mean I only need to set these in rc.conf?:
performance_cx_lowest="C3"
economy_cx_lowest="C3"
Then run /etc/rc.d/power_profile 0x00?
It short - yes. In long - read the link I've given.
May it cause any instability?
It you won't switch from LAPIC to other timer and it stop - your system
will freeze, or at least not work well. You should notice problems
immediately, if there are.
This is 8-STABLE, any idea whether there's a MFC plan for the extra
9-CURRENT bonuses?
I suppose around May.
Do you have some patches? If not you don't really need to make them just
for me, I can wait a little.
Last ones I've generated are five months old:
http://people.freebsd.org/~mav/timers_merge/
They are large and I am not sure how good they apply now.
You may want to look here:
http://wiki.freebsd.org/TuningPowerConsumption
From reading this, are you reffering above to the C2 states? (seems
like C3 is not optimal for this kind of operation...)
The deeper state, the more power saved. To get most of it and to get
TurboBoost working you need at least C3 CPU state (ACPI may report it
with different number). Some latest Intel CPUs have no described
problems with C3 and LAPIC, for others described system tuning
requited.
I believe this is pretty recent CPU (6 core Xeon X5650). Do you know
about any problems?
I have no idea about these Xeons. I know just that LAPIC of the my Core
i5 works fine in C3, while one of the my Core i7 doesn't.
PS: Using powerd in best case wont hurt performance, while using
C-states may even increase it in some cases because of TurboBoost.
If I want to use C-states, should I stop to use powerd, or is it
possible to use them both together?
I am using both together on my laptop.
--
Alexander Motin
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