[mythtv-users] Freevo, Tivo & MythTV

Simon Allcorn simon.allcorn at gmail.com
Mon Nov 20 09:02:16 UTC 2006

Hey, not seen the rest of the thread as its quite large, but looking
at the snippet below, it's my understanding that linux tries to use as
much memory as possible all the time - if it's not used by
programs/data it will use the rest as a file cache, aiming to keep and
small amount (like below - 5Mb / 512Mb) free all the time. So if we
need to use more memory for programs we will dump some of the file
cache and give up that memory to a program. So in theory we should
never use sawp if we have any file cache available, however nothing is
perfect and I had a problem on a box a while ago were it seemed that
once file cache memory had been allocated it would not get
de-allocated, which meant swap filling up and getting lots of OOMs,
which was nice :)

Anyway the point I want to come to is there is a /proc file called
something like 'swappiness' which allows you to tune how aggressively
memory is swapped to disk. Not sure if this is helpful, I'm 98% sure
the above is correct.

Enigma's file server appears to be doing next to no work, since it's
only using ~62Mb of RAM for code and data, and I guess you would
expect more disk cache usage on a file server.

On 11/20/06, David Brodbeck <gull at gull.us> wrote:
> Enigma wrote:
> > Huh?  My file server which has been up for 56 days has 512 MB of RAM, it
> > is showing 5.6 MB free RAM and is using 450 MB for disk cache, but is
> > only using 140k of swap.  A MythTV Slave BE/FE box with an uptime of 3
> > days has similar stats, 512 MB total, 5.4 MB free, 278 MB cache and 28k
> > of swap.  If you are really swapping out that much I would suspect you
> > had a memory-hungry application open at some point.
> >
> Probably mythfilldatabase.  It takes up a good chunk of RAM.  On my 256
> MB frontend/backend system with 512 MB of swap, I come within a gnat's
> whisker of running out of swap when it runs.
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