From: Herbert Poetzl (herbert_at_13thfloor.at)
Date: Mon 19 Jul 2004 - 15:22:45 BST
On Mon, Jul 19, 2004 at 11:02:36AM +0200, Gebhardt Thomas wrote:
> On Friday 16 July 2004 15:43, Herbert Poetzl wrote:
> thank you very much for your answer:
> > here are some facts:
> > - the VM is called AS at kernel level for good reason,
> > because it's not virtual memory but Address Space.
> > - ps calls it VMZ for whatever reason.
> > - vserver-stat is legacy compatible in the output, and
> > jackques decided to label it VMZ but display it in
> > MB which is just another variation ...
> > - the AS can be large, sometimes larger than the
> > RAM + SWAP space even for one process (ask SUN about
> > that ;)
> > - it doesn't make much sense to account address spaces
> > only once, just because they point to the same data
> > either in memory or swap ...
> Ah, I see. So VSZ is actually the accumulated amount of address space
> within a vserver.
> Is there a tool to estimate the actual (virtual) memory consumption
> of a specific vserver? Just to answer the question: my box has x GB RAM
> and y GB swap space: how many vserver of that type will fit onto that
not at the moment, but you can use a simple trick for that:
- start a specific test vserver
- stop it again (this warmes up the caches)
- now get the current memory usage
- start the vserver the second time
- again get the current memory usage
- now build the differences ...
this will vary from run to run, but it's a good estimation
and I'd suggest to stop putting vservers on the machine
as soon as they start to swap out (because this is a good
sign, that your machine will not handle much more without
impact on overall performance)
> > - RSS (Resident Set Size) is something completely
> > different, it's the ammount of data resident in the
> > system memory (available from RAM) ...
> That's another odd item. The RSS values reported by vserver-stat
> are ridiculously small (maybe off by a factor of 1024?). Just a few kB
> per active vserver running apache.
give some numbers, and we'll discuss them ...
- vserver values
- values of the processes inside
> Cheers, Thomas
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