Re: Linux max on shared buffers?

On Wed, 10 Jul 2002, Chris Albertson wrote:

> What I have found, on a machine that is doing mostly DBMS servering
> if you have a small shared buffer you will see that the CPU is
> not fully utilized as it is waiting on I/O a lot of the time.

What OS are you using? Unless it's really strange or really old, you
are probably just removing an operating system buffer for each shared
memory buffer you add. (But this is not good; two smaller buffers in
series are not as good as one big buffer.)

> I keep adding buffer space until the CPU utilization goes to
> ~100%. Adding more buffer after this does little to speed up
> querries. I use the "top" display under either Linux or Solaris.

Um...I just don't quite feel up to explaining why I think this is
quite wrong...

cjs
--
Curt Sampson <cjs(at)cynic(dot)net> +81 90 7737 2974 http://www.netbsd.org
Don't you know, in this new Dark Age, we're all light. --XTC