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SubjectRe: output of `free`
On Tue, 25 Mar 1997 bofh@snoopy.virtual.net.au wrote:

> Here's the output of running `free` on one of my systems (2.1.29).
Is it right to have more shared memory than physical RAM? A quick
inspection of the kernel source indicates that the code goes through a map
of physical RAM and counts pages, therefore shared should be less than
total RAM (the machine has 32megs). Is something wrong or am I
misunderstanding this?
>
> total used free shared buffers cached
> Mem: 30760 30360 400 54084 188 2544
> -/+ buffers: 27628 3132
> Swap: 127004 7248 119756

My limited, non-expert understanding of this is that every process gets its
shared memory region counted. This implies that shared memory can be
larger than actual memory. ie, given the following:

process shared region and size

1 A (300K)
2 A
3 A
4 B (500K)
5 B

The total shared memory shown in free is 3*A + 2*B = 1900K.


Actually, I am interested in uncovering another number concerning
ramdisks: the actual amount of memory dedicated to ramdisk or ramdisk
like memory (my understanding is that ramdisk pages are a specially marked
page).

This is interesting if one is operating a number of ramdisks, and one
would like to know how much memory is actually available for processes
before assuming that free+buffers means anything useful.

Oh, yeah, thanks to whomever replied to my plea for help on initrd... it
sparked a thought in my head (dangerous, I know) and I detected my
problem: real-root-dev was not receiving a value it liked from /linuxrc,
so it defaulted to /dev/fd0, ho hum.

--
William Burrow -- Fredericton Area Network, New Brunswick, Canada
Copyright 1997 William Burrow
"Well, let's just say, 'if your VCR is still blinking 12:00, you don't
want Linux'". --Bruce Perens, Debian's Fearless Leader
** Those who send MAKE.MONEY.QUICK mail, should be sent to Albania. **


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