Re: cachepct limit !

[Pailloncy Jean-Gérard <pailloncy@ifrance.com>]

> The kernel has a limited virtual memory space.
>
> That is the final answer; what you are doing here is entirely pointless
> since you are mucking with buttons you don't have a clue about.
[skip...]
>> I try to raise the cachepct with config so postgresql will be happy.
>>
>> But I got a limit of 26% of my 1Gb of RAM.
[skip...]
>> The memory allocated by the kernel at boot time:
>> - grows lineraly with cachepct under 26%
>> - stay at 280363008 over 26%
For completeness and I hope that will help the next guy asking for this 
question.

The kvm use at the maximum 768 Mb of memory.
And it refuse to reserve more than 35% of the kvm.

I have 1 Gb so kvm use 768 Mb.
And 35% of 768 is 268,8 Mb.
And 268,8 Mb is close to 26% of 1 Gb.

Conclusion : There is nothing to win by setting cachepct
- larger than 25% of your ram if you have less than 768 Mb.
- larger than 268,8 Mb if you have more than 768 Mb.

This applies to OpenBSD 3.3 and 3.4 (I don't have check for other 
versions).

This may change later: in the code there is a note about UBC.
(  /* XXX - This needs UBC... */ in arch/i386/i386/machdep.c)

> You have the source code.
Thanks for the advice. I found the answer in the code this time.
(At this game, I don't win each time)

>   If it is not documented, why are you pushing
> the button?
cachepct is documented is config man page, so I push it.
But not the limit, so I push too much.
And I do not consider the source code as man page. This may change. ;-)

Thank you for all the work, Theo.

Jean-Gérard Pailloncy