[ltp] hdparm settings?

[Nathan Kurz]

On Sat, Feb 19, 2005 at 01:20:53PM +1300, Christopher Sawtell wrote:
>   I wonder if all the different numbers are being caused by folks
> having different settings for their CPU speed settings
> i.e. throttling levels etc.?

Interesting.  I hadn't considered that possibility, so I tried it.

# cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq 
  1197000
# hdparm -t /dev/hda
  /dev/hda:
  Timing buffered disk reads:   54 MB in  3.01 seconds =  17.93 MB/sec
# hdparm -t /dev/hda
  /dev/hda:
  Timing buffered disk reads:   60 MB in  3.05 seconds =  19.67 MB/sec

# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies 
  1197000 798000 

# echo 798000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed 
# cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq 
  798000

# hdparm -t /dev/hda
  /dev/hda:
  Timing buffered disk reads:   60 MB in  3.07 seconds =  19.54 MB/sec
# hdparm -t /dev/hda
  /dev/hda:
  Timing buffered disk reads:   60 MB in  3.07 seconds =  19.54 MB/sec

So an interesting hypothesis, but on my system at least it doesn't
seem to have an effect.  

--nate

BTW, I'm normally running powernowd, and finding it to be a very
effective solution for selecting CPU speed on demand.  Obviously, I
turned it off before I ran these tests.  I did, right? :)