[mythtv-users] backend memory usage

[Simon Hobson]

Josu Lazkano <josu.lazkano at gmail.com> wrote:

> I notice that my backend use to take all available memory.
> 
> I use to monitor the backend with Cacti, here are some graphics:
> 
> Daily physical memory: http://postimg.org/image/hony65809/
> Weekly physical memory: http://postimg.org/image/8mojylnf5/
> Monthly physical memory: http://postimg.org/image/e33l5iejj/
> 
> Is this normal?

As I type, the images aren't loading for me - but I assume they show near enough 1§00% memory usage nearly all the time. If so, then yes, that's completely normal and you should be worried if it wasn't like that.
All decent OSs will dynamically cache data read/written from/to disk - on the basis that it may well be wanted again in the near future. The cache will grow until all the memory appears to be in use if you simply look at the "free" amount. You can see this effect dramatically when booted off a live CD/DVD - the first time you type a command you'll see the disk access and there will be a delay. If you then use the same command again it will fire up instantly.

"top" will who you the cache size, as will "cat /proc/meminfo".

You can force teh OS to fluch and drop the contents of caches with something like "echo 3 > /proc/<something I can't remember offhand/drop_caches" (use ${favourite_search_engine} for exact file). You'll then find yourself with free memory and can watch it fill up again - and the system run more slowly while it does it.