Ivan Prenosil wrote:

> Alexandre Benson Smith wrote:
>
>> Reduce de Cache Size to something between 8000-10000. There is a known
>> limitation on the FB 1.X dirty page algorithm that tends to slow down
>> with Cache Size greater than 10k. FB 2.0 can handle bigger caches
>>
>
> The number 10000 is just myth.
>

I won't call a myth, but a "guide"number.

> Actually there is no "magical" number of pages after it is slow.
> The old algorithm simply means: the bigger cache, the slower.
>

yes, but I tink the slowness are not an arithmetic progression, I think
a kind of geometric progression.

But I had never did any measurement tests.

> The slowness is caused by "eating" more CPU power.
> But this problem was discovered many years ago - with todays CPUs
> you will hardly notice any difference.
>

I did not know this, bu I think it is not too small nowadays, because
the core developers will not change it if it is not applicable anymore,
and it's emphasized on Release notes.

> (a year ago I tried to test whether the algorithm was improved
> in FB1.5 or FB2, but the difference between FB1 and FB2 was so small
> that it was not worth to remember the result)
>

I know you are an experienced guy, and that you don't believe what
others says and always test it to make your opinion. I tend to believe
what the others says :-)

But how did you make your tests ?
Concurrent connections trying to trash the cache entered the game ?

> Ivan
> http://www.volny.cz/iprenosil/interbase/
>
>

thanks for your comments.

see you !

--
Alexandre Benson Smith
Development
THOR Software e Comercial Ltda
Santo Andre - Sao Paulo - Brazil
www.thorsoftware.com.br