Managing Kernal resource - Mailing list pgsql-general

From Ashish Karalkar
Subject Managing Kernal resource
Date
Msg-id 004201c7a9b1$147efa80$170211ac@LIONKING.COM
Whole thread Raw
Responses Re: Managing Kernal resource  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
Hello All,
 
I think I am little bit lost in congiguration of SHMMAX parameter.
 
As per documantation on :
 
 
NameDescriptionReasonable Values
SHMMAXMaximum size of shared memory segment (bytes)512 KB + 8192 * buffers + extra ... infinity
 

"The most important shared memory parameter is SHMMAX, the maximum size, in bytes, that a shared memory segment can have. If you get an error message from shmget along the lines of Invalid argument, it is possible that this limit has been exceeded. The size of the required shared memory segments varies both with the number of requested buffers (-B option) and the number of allowed connections (-N option), although the former is the dominant item. (You can therefore, as a temporary solution, lower these settings to get rid of the failures.) As a rough approximation you can estimate the required segment size as the number of buffers times the block size (8192 KB by default) plus ample overhead (at least half a megabyte). All error messages will contain the size of the failed allocation request. "

 
 
 
As far as I understood is 512 KB+8192*number of buffers times the block +0.5M.B
 
But I am not getting the count of number of buffres.
In postgres.conf file there is size of shared buffer.
 
shared_buffer=24 MB.
 
can anybody point me to number of buffers if i have understood correctly
 
 
Thanks In advance.
 
With Regards
Ashish...
 
 
 
 
 

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