[VU+ Duo] Free memory on VU+ Duo running ViX 2.3

[slain]

I've been having random lockups (no crashlogs created) running ViX 2.3 since release, and I've stuck with it to see if the issues are rectified with 2.4. Today I noticed the following whilst logged in via SSH:

# free
total used free shared buffers
Mem: 138272 116464 21808 0 656
-/+ buffers: 115808 22464
Swap: 0 0 0

That seems to suggest that there is 135MB of physical memory available to the system. The thing is, I was under the impression the Duo comes equipped with 384MB of RAM. As you can see from the -/+ buffers, there is very, very little free memory to play with, and that's very shortly after boot.

# uptime
12:34:14 up 56 min, load average: 0.13, 0.07, 0.09

Without wanting to revert back to an older version to test, can anyone let me know if they see similar results to this when logged in via SSH/telnet? Do older ViX versions show this amount of memory on a Duo?

I'd expect the kernel to report the full amount of physical memory when running "free" on any UNIX platform, in this case something like 393216. If the developers can explain why the memory is reported in this way then that's fair enough, but I'm getting the impression the box is crashing due to the OOM killer before the kernel panics, hence no crashlogs.

Could it be an issue like the following reported MIPS kernel problem? http://stackoverflow.com/questions/7526941/configuring-physical-memory-for-linux-kernel

 

[Rob van der Does]

Correct: the amount of RAM that is available is shown. The 'missing' part is reserved for other purposes (such as video).

And as I tried to explain several times before:
Linux tries to use all the memory in your system. But it knows which memory it can discard immediately, such as disk cache and buffers. You can add the memory indicated as cache and buffer to your free memory. When you do so, you will see that you'll probably have much more memory available. I guess more than 10MB.
You should look at "Free + Cached + Buffers", and under normal circumstances, Cached is over 50MB, which means there's >50MB available for use.

Execute 'top' or 'cat /proc/meminfo' to get the cached and buffers numbers.

Activating swap will not give you more free memory. But it will provide more memory when it is really needed.

And regarding 'free memory': "Free" is in this context the same as "Wasted". You don't want Free memory, you want the memory to be used for anything that helps performance, such as cache.

So: With Linux, by default all available memory is used (for buffers and caching). It will be released when applications require it.

The memory reported by 'top' is ADDRESS SPACE, not actual RAM. That's how you can get >100%

 

[Trial]

Hi,
the kernel reports the usable amount of memory. The rest is used by the box internally like frame buffer ans so on.

With Linux you have very seldom a lot of free memory because the unused memory is used very intelligent for cache and buffer. There is no need to worry unless you get a report "out of memory" somewhere.

ciao

 

[slain]

Correct: the amount of RAM that is available is shown. The 'missing' part is reserved for other purposes (such as video).

That was the part that I needed confirming, thanks. I wasn't sure if the framebuffer etc. was shared or not. I'm guessing that I've got a bloated/rogue plugin running or something of that ilk, as I have very little buffered or cached. I previously had project-valerie installed and have a feeling that might have left some remnants behind.

Gotten rid of LiveFootball too, which crashes half the time anyway so I stopped using it.