[Puppet Users] Re: Magazine article comparing CPU usage of Puppet vs. Cfengine

Thomas Bellman
2010-02-24T00:10:12Z

Trevor Vaughan top-posted:

> Just out of curiosity, do the ones that take longer happen to be 64 bit?

Well, yes, they are indeed 64 bit (x86_64).  But that doesn''t
distinguish them from the quicker ones.  They are all running
CentOS 5.4 for x86_64, and they all have identical quad-core
Opteron CPUs and identical motherboards, RAID controllers, and
disks.

There are differences though; some machines have dual processors
(i.e. 8 cores) with 32 Gbyte RAM and run Xen, while some have
single processors with 16 Gbyte RAM and do not run Xen.  I haven''t
seen any *obvious* correlation between speed and non-Xen, dom0 or
domU, or with amount of virtual CPU:s or RAM assigned to the
domains, but as I said I haven''t really had time to analyze the
problem properly.

> Also, does using --tags do what you want in terms of testing speed?

It does speed things up, yes.  I have tried to use it, but:

- You need to list all classes you have changed.  Easy if you
   have only touched one class, but sometimes changes affect
   multiple classes.  (They might all be included from some
   common class, but then you need to look up the name of that
   class.)

- When you use inheritance, it seems that you need to list the
   base class, not the class you actually include().

- I want to make a final test run with the entire configuration
   anyway, so I know I haven''t broken something I didn''t
intend.
   If I don''t use --tags I get that for free.

- The speedup isn''t really that great.  It helps, but it only
   takes a slow node from 30 seconds to 20 seconds, or a quicker
   node from 15 to 10 seconds.

Altogether it means that remembering to use --tags is barely
worth it.


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