It's not actually too difficult to do this, if you have some hardware
with lots of CPUs. With Solaris 8, you can create "processor sets",
grouping a number of CPUs together, then running processes on those
CPUs, they will not get any cycles scheduled on other CPUs in the
system. This is different from Logical Partitions, because it only
affects CPU, not memory, disks, etc. See psrset(1M) for more details. It
would be trivial to script the creation of different sized groups, start
Oracle on a group and run a benchmark, shut down and resize the group
and so forth.
The concurrency of the application makes a huge difference. My
multithreaded application, with a single open connection to Oracle
performing transactions sequentially is capable of 7.8 (fairly involved)
transactions/sec on a quad-SPARC. But, through experimentation, I have
discovered that, in my specific case, having 33 connections and
transactions running in parallel gives me optimal performance (over 26
transactions/sec, the bottleneck is now disk I/O). Transactions per
thread per second went down from 7.8 to 0.79, of course, but overall
throughput was massively improved.
The moral of this story is, performance is a subtle art, and can often
be counter-intuitive unless you understand the underlying principles.
g
-----Original Message-----
Sent: Thursday, August 16, 2001 6:13 PM
To: Multiple recipients of list ORACLE-L
Of course, it would be rather nice to be
able to set up an entire environment
with a high-stress application, and
then run a test which kept the total
available MHz constant but changed
the number of chips. But even then
you'd have to be very careful about what
it was you were actually measuring.
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Guy Hammond
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