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(at)ethereal-realms(dot)org