Cosimo Streppone wrote:
Mark Kirkwood ha scritto:
Cosimo Streppone wrote:
######### Config ############
/etc/sysctl.conf:
kernel.shmall = 786432000
kernel.shmmax = 786432000
I think you have a problem here.
kernel.shmmax should *not* be set to an amount of RAM, but
Sorry, I thought "shmall" but written "shmmax".
Thanks Mark!
Hehe - happens to me all the time!
On the shmall front - altho there is *probably* no real performance
impact setting it to the same as shmmax (i.e. allowing 4096 allocations
of size shmmax!), it is overkill. In addition it does allow for a DOS by
a program that allocates thousands of segments (or somehow starts
thousands of Pg servers on different ports...)!
For a dedicated Pg server I would size shmall using a calculation along
the lines of:
shmall = (no. of postgresql servers) * (shmmax/4096)
If there are other daemons on the box that need to use shared memory,
then add their likely requirements to shmall too!
cheers
Mark
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