Re: SHMMAX / SHMALL Was (Re: postgresql-8.0.1 performance

Martin Fandel wrote:
> Aah ok :)
>
> I've set my values now as follow (2GB RAM):
>
> SHMMAX=`cat /proc/meminfo | grep MemTotal | cut -d: -f 2 | awk '{print
> $1*1024/3}'`
> echo kernel.shmmax=${SHMMAX} >> /etc/sysctl.conf
> SHMALL=`expr ${SHMALL} / 4096 \* \( 4096 / 16 \)`
> echo kernel.shmall=${SHMALL} >> /etc/sysctl.conf
>
> sysctl.conf:
> kernel.shmmax=708329472
> kernel.shmall=44270592
>
> postgresql.conf:
> max_connections=500
> shared_buffers=40000 # ~312MB, min. 1000, max ~ 83000
>

Hmmm - shmall set to 168G... err why? Apologies for nit picking a little
- but shmall seems unreasonably high. I can't see much reason for
setting it bigger than (physical RAM in bytes)/4096 myself. So in your
case this is 2*(1024*1024*1024)/4096 = 524288

Cheers

Mark