[vserver] VSZ and RSS from vserver-stat

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From: Justin M Kuntz (jkuntz_at_prominic.com)
Date: Thu Aug 08 2002 - 15:45:28 EDT


I am very happy with vserver! Thanks to Jacques and everyone for making it
so wonderful this quickly! One of the main problems/questions I have right
now is about the vserver-stat command.

I don't understand the significance of the VSZ and RSS values. I realize
the first is for virtual memory pages in use by the vserver and the second
is for the resident set size, but I'm not clear on the implications of
those values. Does the VSZ always correspond to the actual amount of
memory used by the programs running in the vserver? Or does it count
shared memory multiple times for each lightweight process/thread? I am
seeing some very huge VSZ numbers for programs that should only be taking
up 200-500 MB of RAM, and instead I see 2-3 GB of VSZ pages.

As for RSS - I must admit, I don't understand what this is. Does it have
something to do with kernel structures currently loaded into physical RAM
for the vserver? The values are always so small -- less than 1-2 MB
typically, that I'm not sure I understand the point.

>From an ASP/hosting perspective, it would be very nice to limit the amount
of RAM a vserver could allocate. I know this is on the to-do list and I'm
anxiously awaiting the feature. In the meantime, I'd like to get a better
handle on how the current memory statistics work in terms of these VSZ and
RSS items.

Thank you!

Justin Kuntz
Phone: 217-356-2888 x 101 | Fax: 356-3356 | Pager: 888-241-0647
Internet: jkuntz_at_prominic.com | NotesNet: Justin Kuntz_at_Prominic@Notes Net
"In the middle of difficulty lies opportunity." -- Albert Einstein

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