shared_buffers revisited

Started by Thalis A. Kalfigopoulosover 24 years ago2 messagesgeneral
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#1Thalis A. Kalfigopoulos
thalis@cs.pitt.edu

Another minor issue that has come to my attention is that when I define
shared_buffers=40000
I assume that it'll need a shm segment of 40000*8192=327680000 bytes
And so I set /proc/sys/kernel/shmall and shmmax accordingly only to find out that postmaster failes to start because it requests a shmsegment of 336404480 bytes. Where is the fallacy in my math?

TIA,
thalis

#2Tom Lane
tgl@sss.pgh.pa.us
In reply to: Thalis A. Kalfigopoulos (#1)
Re: shared_buffers revisited

"Thalis A. Kalfigopoulos" <thalis@cs.pitt.edu> writes:

Another minor issue that has come to my attention is that when I define
shared_buffers=40000
I assume that it'll need a shm segment of 40000*8192=327680000 bytes
And so I set /proc/sys/kernel/shmall and shmmax accordingly only to find out that postmaster failes to start because it requests a shmsegment of 336404480 bytes. Where is the fallacy in my math?

Shared buffers are not the only things we keep in shared memory ...

regards, tom lane