Measuring Free memory

Lowell Gilbert freebsd-questions-local at
Wed Mar 17 20:57:52 UTC 2010

Mario Lobo <lobo at> writes:

> On Wednesday 17 March 2010 19:03:03 Lowell Gilbert wrote:
>> First, you'll need a precise definition of what you mean by "free memory".
> Free physical memory available.

Not precise enough to have a clear answer.  Does it have to be zeroed
already, or do clean inactive pages count? [etc. for buffer cache, VM
page cache...]

>> Add the "-H" flag to get that value more precise.  I suspect, however,
>> that precision isn't really the right term for what you're after.
> I caught the -H flag right after I wrote the mail. The result has to be 
> multiplied by 1024.
> It's possible you're right but what I am trying to do is to monitor the amount 
> of free physical memory still on the system. 
> To make a long story short, I am in a long stretch in trying to find out why 
> 8-STABLE amd64+VBox+nvidia driver is freezing my system to power button point.

Ah.  That's different.  Generally it's more useful to track paging
rates, assuming memory has anything to do with the freeze (which may not
be the case).

Lowell Gilbert, embedded/networking software engineer, Boston area

More information about the freebsd-questions mailing list