Re: [Vserver] Wiki : HowTo graph vserver usage with cacti

From: Grzegorz Nosek <grzegorz.nosek_at_gmail.com>
Date: Wed 21 Dec 2005 - 17:51:51 GMT
Message-ID: <121a28810512210951y10649e0dm@mail.gmail.com>

2005/12/21, Herbert Poetzl <herbert@13thfloor.at>:
> > - network traffic (again, somewhat faster than iptables stats, a'la
> > /proc/net/dev maybe)
>
> this will have to wait until ngnet handles it, as with
> the current implementation the iptables accounting is
> the fastest you get (if you are concerned about on
> wire packages) ...
>
> an alternative is the socket accounting, which gives
> an userspace view of transmitted data ...

I'll probably go with iptables accounting for now.

>
> > - reliable memory usage (current implementation apparently doesn't
> > account for shared memory, like libraries)
>
> hmm, please elaborate in what way this affects your
> results (i.e. why would you want to know about the
> shared memory specifically)

I'm not interested in shared memory per se, I'd just like realistic
memory usage stats. E.g. (relevant lines from various status commands)

vserver-stat:

CTX PROC VSZ RSS userTIME sysTIME UPTIME NAME
135 73 1.5G 3.5G 6h25m24 1h36m13 6d15h55 v135

/proc/meminfo (on host)

MemTotal: 1031036 kB
MemFree: 19272 kB
SwapTotal: 508920 kB
SwapFree: 504152 kB

So I apparently have a vserver (one of several) using 3.5G of memory
on a machine with 1G installed and 0.5G of swap (hardly touched at
all), whereas in reality it's just a number of apache2 processes
sharing most of their memory.

>
> > - disk i/o
>
> as in bytes read/written from/to disk(s) by context
> or disk operations or bandwidth?

Ideally, I'd like to see virtualised /proc/vmstat :)

>
> > - process-related stuff, like fork rate might be useful (ideally
> > per-user but that'd be quite an overhead probably)
>
> hmm, fork rate can be deduced by looking at the current
> processes and the number of forks in a timely manner
> (i.e. that should be something the graphing tools do)

Yeah, I think I can just graph total_forks from /proc/virtual/*/cvirt
:) I was trying to put as many ideas as possible.

>
> > Also (although not a monitoring issue and actually not vserver-related
> > really but maybe somebody has a patch handy), I'd love to see per-user
> > rlimits (the PAM-enforced ones are really per-login, so e.g. apache
> > doesn't obey them at all).
>
> hmm, shouldn't you be able to change the pam to make
> them per user? guess this should be an userspace issue

Well, I can't. The limits are enforced by pam_limits.so which isn't
used at all. I don't really care about limiting interactive logins
(hardly any user ever logs on these machines, most don't have shell
accounts). OTOH, I care about per-uid limiting of resources (our web
servers have a per-vhost assigned uid and I'd like to reduce the
possibility of one broken script taking out all other vhosts).

Best regards,
 Grzegorz Nosek
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Received on Wed Dec 21 17:52:10 2005

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