From: Pawel Leszczynski
Sent: Monday, June 16, 2008 3:18 PM
Hello everybody,
recently, as our production LPARs apetite for CPU has grown meaningful
(we are in process connecting succesive branches of bank to new
application),
our sysprogs decided to simply put online subsequent processors to
this
LPARs.
We ended in 12 processors assigned to each of them.
I would like to know if 12 processors/LPAR is not too many, i.e.
measure how much capacity it 'wasted' that way.
I realise that RMF monitor III shows overhead on let's say LPAR
dispatching
but I guess that's a different story.
Where is this CPU 'wasted'?
That's my naive thinking (please correct me):
Serialization beetween processors within LPAR is done via locks.
Requests for spin lock (from this point of view) are 'CPU-wasting' -
processor
have to wait actively (if wait at all) for obtaining such a lock.
Where are other places???
Is there any tool which sums such 'CPU-wasted' cycles and shows how
many
percent of CPU is 'wasted' in such way?
Regards,
PAwel Leszczynski
PKO BP SA
We need a little more information here. For example, what are the total
number of physical processors? One rule I've followed is that you don't
want to have the number of LPs to be more than 2.5 times the number of
PPs. That might be a little outdated, I don't know, but it's what I
use.
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