shared_buffer setting - Mailing list pgsql-general

From km
Subject shared_buffer setting
Date
Msg-id 20061006154003.GA17390@mrna.tn.nic.in
Whole thread Raw
Responses Re: shared_buffer setting
List pgsql-general
Hi all,
Iam using postgresql 8.1.4 with 8GB physical RAM.

OS kernel max shared memory usage is set to( /proc/sys/kernel/shmmax) 33554432
dont know if this number is in bytes or bits
now how do i set my shared_buffer setting in postgresql.conf such that ican use max shared memory setting of the
kernel.

also default shared_buffer setting is 1000 - its not clear if i have to multiply this number with 8KB to be <= max
sharedmemory value or it is 1000 bytes or bits.  
can i set the max shared memory value to use atleast half of my physicl RAM available ?
any idea ?
also i would like to know how is the performance hit when we change shared_buffer value in general ?

regards,
KM

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