[ubuntu-mythtv] Performance tuning for Mythbuntu

[Steven Ellis]

Some good tips there, most of which we already use on myPVR.

I have a couple you missed to throw into the hat.

1. Enable "Delete Files Slowly" as the defauly. Causes a massive reduction
in I/O regardless of the filesystem in use, but in paticular if you use
ext3/reiser.

2. Tuning for IVTV driver to prevent memory issues. Simply add the
following to /etc/sysctl.conf for upto two IVTV tuners
vm.min_free_kbytes=16384

I've found with 4 tuners we had to raise this to 32768.

3. Thresholds for cpu scaling.

This can be an interesting one to tune. I set this up on our units because
it helps keep the temperature under control, but you need to make sure the
cpu scales quickly enough when required. At the moment my settings are as
follows, but I haven't seen how well it adapts to an OTA HD feeds

echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo 70 > /sys/devices/system/cpu/cpu0/cpufreq/ondemand/up_threshold
echo 1 > /sys/devices/system/cpu/cpu0/cpufreq/ondemand/ignore_nice

I added ignore_nice as it keeps the box quiet and cool when performing
commflag or transcode jobs.


Steve

--------------------------------------------
Steven Ellis - Technical Director
OpenMedia Limited - The Home of myPVR
email   - steven at openmedia.co.nz
sales   - sales at openmedia.co.nz
support - support at openmedia.co.nz
website - http://www.openmedia.co.nz