[hobbit] question on memory swap for Darwin clients

[Dominique Frise]

Henrik Stoerner wrote:
> On Tue, Apr 18, 2006 at 10:13:10AM +0200, Dominique Frise wrote:
> 
>>Henrik Stoerner wrote:
>>
>>>It's a bug. There is no swap information in the Darwin vm_stat output,
>>>so it shouldn't be reporting those at all.
>>
>>There is
> 
> 
> Clue me in. Which bit of this info is about swap ?
> 
> 
>>[meminfo]
>>Mach Virtual Memory Statistics: (page size of 4096 bytes)
>>Pages free:                   154609.
>>Pages active:                  45696.
>>Pages inactive:                34172.
>>Pages wired down:              27667.
>>"Translation faults":      702133041.
>>Pages copy-on-write:       110185692.
>>Pages zero filled:         148901972.
>>Pages reactivated:             26786.
>>Pageins:                     3864958.
>>Pageouts:                      27880.
>>Object cache: 18823165 hits of 23019598 lookups (81% hit rate)
> 
> 
> I can understand the Pageins/Pageouts. But that sounds like swap
> activity, not how much swap is used.
> 
> 
> Henrik
> 
> 
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> 
Sorry my mail get sent to quickly!

---Extract of http://forums.macosxhints.com/archive/index.php/t-30544.html---

By default OS X will use a 64mb swap space file until it needs to allocate more 
- a 256mb swap space with over 100-200 thousand pageouts is a good indicator of 
memory starvation.

Pageouts through time is the most interesting metric, as that will tell you how 
much the OS has moved out. Of course, even this doesn't quite tell you the 
complete story, as there can sometimes be bursts of activity when it doesn't 
have too much effect otherwise.

One good indicator of needing more memory is if, while doing whatever you 
consider normal work on the machine, the pagout count continues to climb, but 
don't watch right after booting/logging in as there will be some initial change 
at that time.

The other is to watch how many swapfiles exist in /private/var/vm which is 
affected by pageouts which haven't been brought back in.
--------------------------

In other words, yes, it is not so trivial to watch the swap/pageouts activity 
on Mac OSX ;-)

Dominique