RE: Any exp with NTw/2 to 4 hamster wheels?

Every once in awhile a really tasty morsel comes floating down the pike. Yum.

One thing for certain - when you go from 2 to 4 CPUs, Task Manager gets twice as many graph windows in it. I've never seen 4 hamsters running on a single wheel. Maybe you could get 4 mice on a wheel at once, but I don't think that there's enough 'wheel width' to support 4 hamsters without "King of the Hill" ensuing.

Today's (and yesterday's) phrase of the day (for me) is .... <drum_roll>

PROCESSOR AFFINITY and its buddy

CACHE WARMTH Even if your CPUs aren't maxed out, running more processes than CPUs will mean context switches for other processes, which will overwrite the data stored on the local CPU cache. It may seem like I'm just dreaming about big iron (I am) but there exists some validity to the premise of doubling the number of CPUs should halve the frequency in which your process is told to take a seat.
You can muck around in the registry (compaq has literature on this) and attempt to set affinity of processes to processors, but you're much better off to just strip everything else off of the OS (disable, can't recompile) and let Oracle run itself.
I assume that the box has multiple PCI bus channels (64 bit) and dual memory controllers? What's the point of putting 4 x 1 GHz CPUs in a box with anything less?
How many RAID controller channels are you using? How much cache? What's the networking configuration - quad port Fast Ethernet or Gigabit? How much RAM is currently in the box?

Where are your current bottlenecks - say for example the online redo logs? Having the same number of processes trying to run faster may just lead to a larger value of the wait statistics. At least you can use a larger number of database writers and archivers - if your I/O can support them.

The current marketing info drones on as saying "Windows 2000 handles mutli-tasking much better than WinNT Server 4.0 ..." so you're probably better off to use the "new and improved" hamsters.

By the way (donning the asbestos) if you run x86 Solaris or Linux on it, is it still just a hampster wheel? :)

Looking forward to a dual-hamster-wheeled Athlon box myself sometime soon ...

Paul

I gotta get my home email account straightened out before this gets me in trouble ...

-----Original Message-----
From: Charlie Mengler [mailto:charliem_at_mwh.com] Sent: Wednesday, December 06, 2000 4:37 PM To: Multiple recipients of list ORACLE-L Subject: Re: Any exp with NTw/2 to 4 hamster wheels?

If the two existing CPUs are under utilized, add two more CPUs will have limited or marginal benefit; if any measurable affect.

As a general rule only when a resource (memory, CPU cycles, disk I/O throughput, network bandwidth) is be run at 100% of capacity will much be gained by adding more of that resource.

For example assume that you have 1" wide water pipe that can carry 10 liters per second, BUT it is only carrying 5 liters per second. Changing the pipe to be a 2" pipe will NOT change the 5 liter per second flow! The water in this case is flowing at 5L/Sec because of some other bottleneck that is restircting the flow. To make the water flow faster than 5L/sec. you need to identify & eliminate the bottleneck.

The term "bottleneck" is used because it is the neck of the bottle that limits how quickly the bottle can be either filled or emptied. Changing the size of the bottle will not affect the rate at which the water can pass through the neck of the bottle.

HTH & YMMV! "Eric D. Pierce" wrote:
>
> i think a better question is: "why *wouldn't* you see a performance
> increase?". you put more hamsters on more wheels, more things will
> spin around faster w/ greater torque, no?
> ep
>
> On 6 Dec 2000, at 6:20, The Oracle DBA wrote:
>
> > A client seems to be seeing now perf improv with adding 2 more
> > procs to a 2 proc NT box. Anyone see a similar result? This is 805
> > on NT 4.0 SP5.
>

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Author: Charlie Mengler
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