[mythtv-users] Planning Tuners and Disk I/O for a MythTVBackend System

[MythTV]

> > I have a backend/frontend running Ubuntu 9.10, and the response of
> the
> > system would get quite sluggish after running a while.  I found ghat
> > setting "swappiness = 0" made a major difference (google
"swappiness"
> > for specifics).  Now my backend never uses swap unless it absolutly
> > needs to.    My machine has 4GB of ram, so your results may vary.
My
> > machine generally uses 1.8gb of ram for programs, and the rest for
> > cache (I only have 3.6gb of my 4.0gb available; my onboard video
uses
> > the rest)
> >
> > Good luck

Googling swappiness brought the following:

You can make some tweaks to your /etc/sysctl.conf file in order to free
up memory faster. As an example I have these for my MySQL database that
MythTV uses:

# Control the degree the kernel prefers to swap when trying to free
memory (default 60)
vm.swappiness=0

# Reclaim cache memory faster for directory and inode objects (default
100)
vm.vfs_cache_pressure=10000

# Let dirty data consume this percentage of memory (default 10)
vm.dirty_ratio = 1

# Let dirty active data consume this percentage of memory (default 5)
vm.dirty_background_ratio = 1

# Wake up pdflush to write to disc (default 500)
vm.dirty_writeback_centisecs = 250

# How old data can be before it should be considered dirty and written
to disk (5min) (default 3000)
vm.dirty_expire_centisecs = 3000


I've applied them to try.  Sounds like they limit the number of dirty
pages, but increase the
amount of time they are allowed to stay in memory.


Any comments?