Re: [Qemu-devel] kqemu vs Standard

[Jason Brittain <jason@brittainweb.org>]

Magnus Damm wrote:
>>
>>Interesting!  I wrote the email about all this while riding to work on
>>the subway.  So, when I did the "cat /proc/cpuinfo", I was indeed running
>>on battery power.  But, currently, I'm not, and still says the same thing.
>>
>>Anyone know what the deal is with that?  Is that an accurate number
>>saying that my cpu is throttled down?  Could I make it run faster then?
>>Hmmmm..
> 
> On a 2.6-kernel with cpufreq enabled, have a look at the files in
> "/sys/devices/system/cpu/cpu0/cpufreq/". Try to echo "powersave" or
> "performance" to scaling_governor. Then look at "/proc/cpuinfo" to see
> the actual MHz.

Ahh, yeah.  I did:

# echo "performance" >> /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

And now my /proc/cpuinfo looks like:

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 13
model name      : Intel(R) Pentium(R) M processor 1.80GHz
stepping        : 6
cpu MHz         : 1799.038
cache size      : 2048 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr mce cx8 mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss tm pbe est tm2
bogomips        : 3563.52

BUT, I retried my tests and the performance numbers/timings came out the same.

> You can also play around with acpi throttling in
> "/proc/acpi/processor/*/throttling". I guess * should be replaced with
> CPU0, but on my crappy laptop with wierd acpi info CPU1 must be used
> instead of CPU0.
> 
> Also, try cpufreqd or cpudyn to adjust the cpu frequency on the fly.

Thanks for the tips on those.  I'll look into them.

Darryl Dixon wrote:
 > That's just the natural effect of the Speedstep technology throttling
 > back the cpu to lower heat because you aren't using many cpu cycles at
 > the moment (you aren't pushing your laptop very hard :).  If you were to
 > do something like, say, compile Wine, and while it is compiling cat
 > /proc/cpuinfo, you would see that the speed is up at 1800MHz.

I believe this, since the CPU performance turned out the same either way.
More good info..  thanks!

-- 
Jason Brittain