Martin Rosenberg wrote: > On a related note, This system used to have 512 Mb RAM. Between the last > tests, and this test, I've upgraded to 1 Gb. I've noticed that my caches > and buffers are still usually taking up nearly all of my memory, and there > seems to be about 300 Mb of unaccounted memory missing. I don't think > this has anything to do with aufs, but aufs may have been getting sad > because of the lack of memory. > To reiterate: everything seems to be good.
Let me explain how does Linux manage memory. First, if you have 1GB of physical RAM on board, Linux can't see 1GB unless you have 4GB support in Kernel. In your kernel config there is: CONFIG_NOHIGHMEM=y # CONFIG_HIGHMEM4G is not set # CONFIG_HIGHMEM64G is not set This means, you are telling kernel to NOT SUPPORT whole 1GB, your kernel will only see something around 800 MB or so. If you wish to use FULL 1GB of RAM, you must enable CONFIG_HIGHMEM4G=y in kernel configuration. Second thing, regarding the cache: Linux caches everything you read from harddisk in memory. For example, if you (or the system itself) read 500 MB of data from your harddisk, all the data will remain in memory (for fast access) unless there is a need to use the memory for something else (eg. for applications). It is pretty normal to see ALL THE RAM filled up by caches. This memory is used to cache disk data, but in fact it is considered to be FREE, because if you run some application then Linux will drop some of the cache immediately, as it can still read the data from disk. So if you're interested in the amount of memory AVAILABLE for your work, count Available RAM for you = free RAM + caches. I believe that your problem is NOT related to insufficient of memory. I hope the explanation will help you understand it better now :) Tomas M slax.org ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
