[CentOS] Memory Usage in Top and System Monitor‏

[Michael McNulty]

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?

----------------------------------------
> To: centos at centos.org
> From: rnicholsNOSPAM at comcast.net
> Date: Thu, 21 Jul 2011 16:28:15 -0500
> Subject: Re: [CentOS] Memory Usage in Top and System Monitor‏
>
> 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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