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CPU clock speed issue
A customer came to me complaining that he could only create VPSs with very low clock speeds on his OpenVZ system. I checked /proc/cpuinfo on his host node and saw that all of his i7 cores were running at 800MHz. I first tried an older OpenVZ kernel and then rebooted into the stock kernel and did the same thing with the same result each time.
The customer is convinced that his hardware is working correctly. I'm leaning toward this being a faulty CPU/BIOS issue and want him to ask his server provider to swap out the CPU to start with.
Does this sound reasonable, or am I being crazy?
Comments
Probably power saving.... recompile a kernel with power saving off or I think you might be able to set the power profile to performance if not
It's worth pointing out that if it is power saving then there's really no need to do anything since the cpu will clock up when it needs to
800 mhz also seem like power saving or some multiplicator stuck to 1x.
It could be bios/motherboard, try without powersaving but i doubt the problem is in kernel.
Exactly what I was doing
These are stock kernels with no special parameters etc.
Yeah stock kernels will power save... You can test if it is on by running a cpu intensive process on the host node and whilst it's running to cat /proc/cpuinfo, if it is power saving then the cpu will have clocked up.
@jhadley have you checked in the bios for power saving mode?
Check the Bios, seen similar option enabled on i7 CPU, which downclocked it to 600-800mhz if I recall correctly. By disabling this option, you should have full clock speed.
There is no customer access to the BIOS AFAIK (this is Hetzner). I've disabled the power management within CentOS and the result is the same. I'll have him contact Hetzner as I originally insisted..
Verify whether or not it is power saving by running a CPU intensive task and checking /proc/cpuinfo whilst it's running.
Can you try this:
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
to see available mode's (my guess it's setup for 'ondemand') and then try something like this:
echo performance >/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
http://en.wikipedia.org/wiki/SpeedStep
Hetzner have suggested the same as @5n1p but actually it's already on performance...
If you load the CPU does the turbo function kick in and raise the clock speed?
As long as it scales up when needed it shouldn't be an issue. Otherwise I'd keep hammering at them to turn it off in the BIOS. There's rarely a need for recompiling a kernel over this.
We've ascertained that it's not a real issue, but the customer in question doesn't want his customers seeing 800Mhz inside their VPSs because he thinks they'll complain (which they might).
I've asked him to relay back to Hetzner.
That command should work, but if it's not check that you have
cpufreq_performance.ko
installed on server. You should see it in:
/lib/modules/"kernel version"/kernel/arch/x86/kernel/cpu/cpufreq/
you can also run:
watch grep \"cpu MHz\" /proc/cpuinfo
and watch if clock speed changes.
you probably have to disable speedstep
I assume you have:
service cpuspeed stop
chkconfig cpuspeed off
?
This.
Tell the customer that this is normal and that this technology has been around for the better part of a decade. Tell him to pass on this info to any of his customers that inquire about it.
He can ask for a Lara (KVMoIP - free for 2 hours) from within his Hetzner robot.
You could then check the BIOS settings and probably disable speedstep from there.