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Just recently my laptop has started behaving weird. It often hangs after a short while of using it (perhaps half an hour), and memory usage is very high. I have 4 GB of memory, and after startup it often uses around 3.8 GB of memory.

This screenshot shows what processes are running and how much memory is used:

http://postimage.org/image/nk4muoxel/ enter image description here I don't think I have installed any new software before this started happening, and I can't think of anything else causing it. My laptop is a few years old now and perhaps it isn't of the best quality, but I don't know if it's possible that some hardware problem could be causing this.

Any ideas?

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Please post your system name or specifications. The Gnome-terminal if edited to use as Maximized on startup causes same problem with my system too.have you updated the system. –  atenz Jul 10 '12 at 6:40
    
Memory is fine (see my other comment: Your apps/processes only use less than 1G, and Linux uses free RAM to speed up things by caching/buffering e.g. file system stuff. As for the "hangs", this needs some more examination. Here you should check with your /var/log/syslog if there are any indications found. Also, are there some patterns like always doing the same thing / using the same app when the "hang" appears? –  Izzy Jul 10 '12 at 8:45
    
Thanks @Izzy, I didn't know how memory is used. Now it makes sense. So it seems my problem was not really about memory usage. I'm thinking the laptop might just have been overheated, sometimes it's as hot as a boiling plate, but that doesn't quite fit under this topic. –  5th Jul 13 '12 at 6:41
    
You're welcome! A good source for further research might be /var/log/syslog, check for any errors that could match. Another nice thing is a monitoring tool such as Monitorix (available via a repository at apt.izzysoft.de, check for details there). Runs right out of the box, draws nice RRD-graphs for almost everything. Really helpful and easy to use. –  Izzy Jul 13 '12 at 7:05

1 Answer 1

up vote 1 down vote accepted

"top" shows how much memory is used including the file caches. This is mostly useless if you try to trouble-shoot memory usage.

Try following:

  1. Use "free" command to see how much memory is actually used, excluding the caches.
  2. Use "top" and press Shift+M to sort processes by memory used.

Normally linux uses all available memory to cache file data - this is exactly what you want it to do as it improves performance. This memory is available anytime to applications if they need it.

From your screen-shot, it is visible that no swap is used so this is a very good indication that you have no memory usage problem.

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Yeah, but it clearly shows cache and buffers. In this case, memory usage even is wonderful: Of the 4GB available, about 1G goes to buffers, and 2G to cache -- what more can one ask from efficient memory management? The "hangs" are a different thing altogether. –  Izzy Jul 10 '12 at 8:42

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