top/ps: is Active Memory = sum(resident set size)?

[Anton Shterenlikht]

This has probably been discussed before, so apology for
asking the same question again.

Should the Active memory, as reported by top(1), be equal to the
sum of rss (the real memory (resident set) size of the process)
of all processes, as reported by ps(1)?
The sum of ps(1) rss fields is probably the same as
the sum of RES fields of top(1).

I seem to have much bigger Active set than the sum of
all resident (or real) memories used by all processes.

Please advise

many thanks
anton

--
Anton Shterenlikht
Room 2.6, Queen's Building
Mech Eng Dept
Bristol University
University Walk, Bristol BS8 1TR, UK
Tel: +44 (0)117 331 5944
Fax: +44 (0)117 929 4423
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[Chuck Swiger]

Hi--

On Jan 12, 2010, at 6:17 AM, Anton Shterenlikht wrote:
> Should the Active memory, as reported by top(1), be equal to the
> sum of rss (the real memory (resident set) size of the process)
> of all processes, as reported by ps(1)?

No. They aren't measuring the same thing; in a system with plenty of available RAM, processes might be entirely resident because there is no memory pressure to start paging inactive pages out, but only be using a fraction of their address space, in which case active per top will be less than the sum of RSS.

--
-Chuck