On 07/21/2011 04:57 PM, Michael McNulty wrote: > > Yes I am copying files there but as my first post shows I have plenty of free memory so I thought it should not be using swap space. > > I guess this is my problem. > http://www.cyberciti.biz/faq/howto-create-linux-ram-disk-filesystem/ > > "tmpfs (also known as > shmfs) is a little different from the Linux ramdisk. It allocate memory > dynamically and by allowing less-used pages to be moved onto swap space. > ramfs, in contrast, does not make use of swap which can be an advantage > or disadvantage in many cases." > > So it looks like I need to use "ramfs" as described here? That sound about right? A ramfs is still using memory. If the remaining memory is inadequate to satisfy the needs of processes, _something_ is going to be forced out to swap. Since that won't be the pages used by the ramfs, it will be pages in use by processes. Whether that is better or worse, from a performance standpoint, than swapping out pages from your tmpfs files is something you would have to determine, but there is no free lunch here. One thing that may be confusing your view of free memory is that a tmpfs uses pages from the buffer cache, and the 'free' command shows that usage in the "cached" category. (No, I didn't realize that, either.) This is a place where pages listed as "cached" are _not_ available to satisfy processes' memory requests. It looks like you need to run "df -t tmpfs" and add up the numbers in the "Used" column to see how much memory falls in the category of "looks like cached, but can't be discarded." -- Bob Nichols "NOSPAM" is really part of my email address. Do NOT delete it.