Обсуждение: shared_buffers revisited

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
requestsa shmsegment of 336404480 bytes. Where is the fallacy in my math? 

TIA,
thalis

"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
itrequests 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