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Disk buffer pushes applications out of RAM?


alvaroag
26-08-2015, 17:20
Mmmm... The swap usage should not be affected. Can you provide the output of "free -m"?

SBRL
26-08-2015, 16:06
@alvaroag So it's normal for the disk buffer to push everything else out of RAM and into swap?

alvaroag
26-08-2015, 13:49
That's normal, I think. The kernel will use as much as needed RAM for memory buffers, and will free it when needed, so you won't have memory problems.

SBRL
26-08-2015, 12:27
Hello,

I have an OVH Classic VPS 1 with Ubuntu 15.10 running on it. Whenever I use a program that reads a lot of different files, (e.g. tripwire), I see through htop that my disk buffer grows drastically and then it starts swapping everything out, and everything gets unresponsive. According to linuxatemyram.com, I don't think it is meant to do this. In addition, the high buffer usage persist across a reboot, even when I uninstall the offending program (tripwire in this case).

Here's what htop looks like when everything is swapped out::



Here's what htop looks like after I've restarted all the processes that have swapped out:



For some reason hardly any ram is used by the applications themselves, even when I've restarted them (if I add up the RES column in htop it totals way more than the 34 MB that free -h reports that I'm using) - but I'm not too worried about that.

If I run sudo "sysctl vm.swappiness", I get a value of "0" returned.

Here's the output of uname -a:

Linux server.name 2.6.32-042stab108.8 #1 SMP Wed Jul 22 17:23:23 MSK 2015 x86_64 x86_64 x86_64 GNU/Linux

Does anyone know what's going on here, and how I can either limit the size of the buffer cache, prevent it from swapping other applications out, or prevent it from growing in the first place?