Todd,

We have customers that use Firebird on PCs with Hyper-threading. We have
never encountered a single problem.

This is what my understanding of the problem:
Using the superserver architecture of Firebird, all database operations are
carried out within the same process. Therefore, when a large query is
performed, this process loads the CPU to nearly 100%. When Windows sees that
one processor is working at around 100% and the other one is nearly idle, it
will take an active process and move it to the other processor. The
objective of this switching is to do some load balancing. Doing so, the load
on the first CPU drops to 0 % and climbs to 100% on the other. Windows will
then switch the process again, and so on. Since switching processors take
CPU time, the end result will be a slower processing of database operations
than when executed on a single processor. On Linux, the same thing occurs.
However, on Kernel 2.4 and above, multiple processors (and Hyper-threading
ones) benefit from the fact that Linux waits a while before switching the
process to another processor. There is therefore less switching.

Using the classic server has the advantage of launching a distinct process
per connection. However, you will run into the same problem if only one
process is taking 100% of the power of the CPU. Switching will occur.

If your client application is on the same PC, Hyper-threading is beneficial.
Your client application loads one CPU (or part of a CPU) and the Firebird
server another part, resulting a faster processing.

Regards

Salim



-----Original Message-----
From: Todd Brasseur [mailto:todd@...]
Sent: Friday, June 11, 2004 3:22 AM
To: firebird-support@yahoogroups.com
Subject: [firebird-support] Intel Hyper-Threading

I don't know much about it .....

Does anyone have any experience with how Hyper-Threading affects
Firebird? Supposedly, Hyper-Threading causes Windows to think that a
machine has multiple processors even though it doesn't.

I was wondering if this could adversely affect Firebase as it has
problems with multiple processors.

Todd







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