OS Overhead

[Burke, Thomas G.]

Since we as yet have no hardware, I'm just looking for "A rule of
thumb," so we can size our processors appropriately.  We're looking at
bitware 8-processor boards, but we're not sure that those will be enough
to do what we're asking in the allotted time, thus I'm lookg for the
"rule of thumb" to appropriately size the processing capacity.  I'm
already down at the "clock tics per instruction" level to see what seems
achievable with *no* OS.  I will assume an inefficiency due to the
compiler, also - of ~15%.

	-Tom 

-----Original Message-----
From: redhat-list-bounces at redhat.com
[mailto:redhat-list-bounces at redhat.com] On Behalf Of Tom Greaser
Sent: Tuesday, January 31, 2006 8:48 AM
To: redhat-list at redhat.com
Subject: RE: OS Overhead


If you need real time / close to real time.. then i agree with Job. 
 but if you just need the proc to be done as fast as possible..
do two things.  put sar on your linux box and see what the stats show
with the box doing NOTHING.. other than its basics..  Then with that
baseline.. you have an idea of what resources you have to tell your
process to use up and where you bottle necks might be (disk, mem swap, )
Now you can deside to use the best kernel scheduler for you demands.
and start the proc up with a nice command ..




      This is a somewhat convoluted question, but here goes...

      We are creating a system that has a "timeline" (e.g. tasks must
be completed in a given amount of time)

      OK, so we have a processor (we'll stay generic at this point)
that will be running a linux based kernel, and we want to figure out how
much processor availability we have (e.g. clock tics in a given time).

      We know that the kernel functions (including resource
allocation, interrupt hadling, and so on) take up some omount of CPU
horsepower (albeit small)

      What is a good general rule of thumb for a barebones linux
system?  I know this is gross estimation, but does the kernel use up 20%
of my CPU resources?  10%?  Any ideas?

      Thanks
            Tom

and message 13

-- 
redhat-list mailing list
unsubscribe mailto:redhat-list-request at redhat.com?subject=unsubscribe
https://www.redhat.com/mailman/listinfo/redhat-list