[CentOS] Memory Usage in Top and System Monitor‏

Robert Nichols rnicholsNOSPAM at comcast.net
Thu Jul 21 21:28:15 UTC 2011

On 07/21/2011 03:20 PM, Michael McNulty wrote:
> --- On Thu, 7/21/11, Robert Nichols<rnicholsNOSPAM at comcast.net>  wrote:
>> Perhaps by not storing so much stuff in it?  That, or
>> adding more RAM. Seriously, if you're going to fill up a large portion of
>> your available memory with a ramdisk, demands for memory are going to have
>> to be met by pushing pages out to swap space.  By default, a
>> ramdisk can grow to up to half of the available RAM after the kernel has been
>> loaded.  If programs and I/O buffers need more than the other memory
>> you have available, what option is there besides swap?
> Actually I am not storing too much stuff in it since there is plenty of free memory. That was the point of my earlier posts asking why swap when there is plenty of free memory.
> Correct me if I am wrong, but I believe behavior is unused files in /dev/shm use swap space? I want to make it so it does not do that since it slows the system down
> and since there is plenty of available free memory.

A ramdisk does not consume any memory at all until you store stuff
in it, and then it uses only such memory as is required to hold its
current contents, i.e., it will shrink again if stored files are
truncated or removed.  From your comment, I presumed you knew you
were actually storing data in /dev/shm.  If you are not, then you
will have to look elsewhere to see what is sometimes consuming a lot
of memory.

Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.

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