Real and availible RAM

Rob MacGregor rob_macgregor at
Mon May 5 08:44:28 PDT 2003

>From: agent dero <dero at>
>I have been looking through the kernel boot messages in /var/log while
>working on some custom kernel compile work, and I came across something
>that I think is very interesting, but doesn't make sense.
>real memory  = 100663296 (98304K bytes)
>avail memory = 94580736 (92364K bytes)

I could be wrong, but if FreeBSD is anything like Solaris what it's telling 
you is that there is 96 MB of RAM installed and that once FreeBSD's kernel 
is loaded there is 90 MB of RAM left.  So, the FreeBSD kernel is using some 
6 MB.

>Also, I use phpSysInfo to judge the status of most of my remote servers,
>and it shows the caches and buffers as part of the whole chunk of used
>RAM, so at one point it can be up to 95% of the RAM. But then 10 minutes
>later it will have dropped back down to 50% or so, showing that the
>buffers were somehow cleared? Is there anyway to do this manually?

I'm pretty sure the full details are lurking in the handbook, however from 
what I understand the caches and buffers are using RAM that's otherwise 
idle.  If something needs that RAM then the caches/buffers shrink.  If 
there's lots of free RAM then they grow.

This is a Good Thing not a bad thing.

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