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 :)
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?
May it cause any instability?
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.
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?
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?
Thanks!
--
Kind regards
Daniel
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