Free phys. memory estimate.

[Mikkel L. Ellertson]

Michael Green wrote:
> How one can tell how much precisely physical memory is free on a given system.
> 
> I mean if I run:
> # free -m -t
>              total       used       free     shared    buffers     cached
> Mem:          2025       1880        145          0         40         87
> -/+ buffers/cache:       1752        273
> Swap:         4109       1723       2386
> Total:        6135       3603       2532
> 
> Looking at the table above I might conclude that 145M is all that's
> left. but apparently this is not so, because a big chunk of RAM is
> used for disk cache and can be quickly released/recovered should a
> portion/all of that memory requested by a malloc.
> 
> I'm trying to fugure out how much physical memory the system has
> available at any given time. How can this be calculated, using what
> numbers?
> 
Use the "-/+ buffers/cache:" line. You are using 1752M and have 273M
free.
> 
> Another question is how a group of users can be limited in terms of memory.
> I have a system here that's starved by IO and I want ot prevent users
> jobs allocating big chunks of swap. say if I have a Linux system with
> 2G of RAM and 4G of swap is it possible to allocate to a _group_ of
> users 1700M only?
> 
You may want to look at the ulimit command.

Mikkel
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