Interesting. So it seems that if you want to track CPU and memory
performance you have to do it at the aggregate VM level. That makes it
difficult to size the guests. How does one know how much resource to give
to a guest. I do understand that if the guest is under-performing then you
give it some more. But by how much?
Very intersting questions...!
__________________________________________
Ranga Nathan / CSG
Systems Programmer - Specialist; Technical Services;
BAX Global Inc. Irvine-California
Tel: 714-442-7591 Fax: 714-442-2840
Adam Thornton <[EMAIL PROTECTED]>
Sent by: Linux on 390 Port <[EMAIL PROTECTED]>
06/17/2004 09:14 AM
Please respond to Linux on 390 Port
To: [EMAIL PROTECTED]
cc:
Subject: Re: Performance Monitoring for Linux
On Thu, 2004-06-17 at 10:29, Barton Robinson wrote:
> I am unaware of any product other than ESALPS on the market
> that is either aware of this problem or addresses
> it. Linux monitors do NOT have the ability to correct this
> problem - they are unaware they are virtualized.
They still have some utility: their absolute numbers--packets per
second, for instance--are accurate. And measurements of Linux processes
vis-a-vis each other (i.e. "Samba appears to be eating about three times
as much storage and four times as much CPU as named") are reasonably
accurate, although that fluctuates a lot in any Linux system,
virtualized or not.
However, yes, as Barton says, anything that measures performance
relative to the Linux image capacity is basically useless, since
effectively the speed of the machine is varying wildly as VM does its
thing (remember that what Linux considers core storage may actually be
out in VM's page space somewhere, so not just CPU performance but memory
access times are enormously variable). So it tells you nothing that
some process is consuming X% of the Linux image's CPU unless you're
either running the image at a fixed priority--which I hope you're
not--or you have some way to correlate that with what VM says the image
itself is doing.
Adam
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