Date: Fri, 6 Jun 2003 10:12:53 -0700
Reply-To: philrack@MINEQUEST.COM
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: Phil Rack <philrack@MINEQUEST.COM>
Subject: Re: Win2K and Dual Processors
In-Reply-To: <20030606161717.GJ31120@ganymede>
Content-Type: text/plain; charset=ISO-8859-1
Actually, I have an OK box right now. Running and AMD Athlon 1400mhz. 1.5gb
ram, 160gb RAID 0 (Promise Controller) and the OS and SAS sitting on a single
7200 rpm 80gb drive with 8mb cache.
What I'm looking for and William answered quite nicely, is if SAS will use both
processors if I was to upgrade to a machine with two. I don't want to spend
the money if the utilization is not there. I do know that SAS V8 is not mult-
threaded so that was the reason for phrasing the question in using two sessions
on a single box.
I've done a lot of exercises playing with stripe sizes and cluster sizes on
RAID 0 and looking at SAS performance. Basically, I've discovered if you set
the stripe size to be as large as you can make it (64k or 128k depending on the
controller) and setting the cluster size to be a either 16K or 32K on the drive
array where your SAS Work space lives the perfomance really shines. DON'T SET
YOUR CLUSTER SIZE TO ANYTHING OTHER THAN THE SYSTEM DEFAULT ON THE OTHER
ARRAY'S OR DISK. You will find that your disk utilities such as defragmenters
and disk checkers will not work.
Finally, you can really improve performance by tuning your environment. I've
posted this before, but Windows 2k, NT, XP only alot 512K to disk caching by
default. If you increase this default to something more reasonable, you will
see a nice increase in performance. Cache Manager - CacheMgr will help you do
this with out playing around in the registry.
You can download this from my website at www.minequest.com and selecting
downloads on the right hand side of the page.
Phil Rack
MineQuest, LLC
SAS Consulting and Contract Programming
www.MineQuest.com
Tel: (614) 457-3714
Fax: (614) 457-9384
E-mail: philrack@minequest.com
Quoting SAS User <sasuser@GUILDENSTERN.DYNDNS.ORG>:
> on Thu, Jun 05, 2003 at 12:18:16PM -0700, Phil Rack (philrack@MINEQUEST.COM)
> wrote:
> > SAS-L'rs
> >
> > I was wondering... if I was using a Win2K Workstation with dual processors
> and
> > had two local SAS sessions running, would SAS (or the OS) be smart enough
> to
> > use both processors for each SAS job?
>
> Under an SMP Win2K system, a given thread can run on any available
> processor, and if my understanig is correct, may alternate among
> available processors if necessary, though its affinitiy is for the
> processor it ran on most recently. Whether or not a given SAS process
> will span multiple processors depends on SAS's threading model. I'm
> not familiar with specifics though the annual SI SUGI Windows presentation
> may cover this.
>
> More significantly, you should pop open the Performance Monitor and
> watch your system's use of I/O, memory, and processor utilization. I
> suspect you'd benefit far more from additional spindles (eg: RAIDed
> disk subsystem) than from more processors, unless you're performing CPU
> intensive taks (some statistics and IML procedures will do this).
>
> For more information, see:
> http://www.oreilly.de/catalog/w2kperf/chapter/ch05.html
>
> --
> Charming man. I wish I had a daughter so I could forbid her to marry one...
>
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