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Re: Re: Cary's book -- Out of stock !

From: Tanel Poder <tanel.poder.003_at_mail.ee>
Date: Tue, 23 Sep 2003 08:39:49 -0800
Message-ID: <F001.005D0D67.20030923083949@fatcity.com>


RE: Re: Cary's book -- Out of stock !Hi!

> Figure 9-14 shows an interesting situation in which a single fast CPU
> out-performs a system with 4 slower CPUs, for a certain condition;
> this is exactly the situation I am facing while testing the move of a DB
> (9.0.1.3.0) from a 2-processor (600 MHz) to a 4-processor (400 MHz)
> box and have been puzzling over reduced performance, even after playing
> with different degrees of parallel query and having twice as much memory
> for the DB on the 4-processor box

Btw, that's one of the reasons why I suggest my clients to turn off Hyperthreading for their new Intel boxes. HT basically makes your CPU to 2 over 50% slower CPUs, providing that all your virtual CPUs will be loaded and you are using the same types of CPU instructions in all of your processes (I doubt that you are using MMX, SSE or even FPU that much with your Oracle database).

Situation gets especially bad with parallel execution where Oracle thinks it has 4 physical processors whilst you actually got 2 for example.

Tanel.

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Author: Tanel Poder
  INET: tanel.poder.003_at_mail.ee

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Received on Tue Sep 23 2003 - 11:39:49 CDT

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