Re: PostgreSQL Performance on OpenBSD

Chris Palmer wrote:
> Martin Foster writes:
>
>
>>However are the above numbers realistic?    This would require some
>>fairly customized kernels for OpenBSD to allow for numbers
>>that high as well?
>
>
> What kernel parameter would need to be changed besides BUFCACHEPERCENT
> (which defaults to 5%)? That's one small customization.
>
>

# PostGRE SQL specific
options         SYSVSHM
options         SHMMAXPGS=4096
options         SHMSEG=256

options         SYSVSEM
options         SEMMNI=512
options         SEMMNS=1024
options         SEMMNU=512
options         SEMMAP=512

All of these options are required in order to start raising the values
of shared_buffers and most probably sort_mem.   Seems that PostgreSQL
uses Posix extensions which are not very well represented in most BSD
kernels.

As a result, you need to manually raise the values above in order to get
higher values.   If memory serves, the above was necessary to have 256
connections with 512 shared_buffers.

    Martin Foster
    Creator/Designer Ethereal Realms
    martin@ethereal-realms.org