Re: Troubles with performances

Warren Vanichuk wrote:
> IpcMemoryCreate: shmget failed (Invalid argument) key=5432001, size=143193088, permission=600

> -o -F -B 2048 -N 512 -S 4096

Ok, you have 2048 8K buffers, and up to 512 backends. If you're trying
to set SortSize to 4096, you need quotes around it and a -o, AFAIK, asx
the -S postmaster option sets silent mode.

Further along,

According to the shmget man page:

The followings are limits on shared memory segment
resources affecting a shmget call:

SHMALL System wide maximum of shared memory pages:
policy dependent.

SHMMAX Maximum size in bytes for a shared memory seg­
ment: implementation dependent (currently 4M).

SHMMIN Minimum size in bytes for a shared memory seg­
ment: implementation dependent (currently 1
byte, though PAGE_SIZE is the effective minimum
size).

SHMMNI System wide maximum number of shared memory
segments: implementation dependent (currently
4096).

The implementation has no specific limits for the per pro­
cess maximum number of shared memory segments (SHMSEG).

And from the linux kernel source, includes/asm-i386/shmparam.h:
/*
* Keep _SHM_ID_BITS as low as possible since SHMMNI depends on it and
* there is a static array of size SHMMNI.
*/
#define _SHM_ID_BITS 9
#define SHM_ID_MASK ((1<<_SHM_ID_BITS)-1)

#define SHM_IDX_SHIFT (_SHM_ID_BITS)
#define _SHM_IDX_BITS 15
#define SHM_IDX_MASK ((1<<_SHM_IDX_BITS)-1)

/*
* _SHM_ID_BITS + _SHM_IDX_BITS must be <= 24 on the i386 and
* SHMMAX <= (PAGE_SIZE << _SHM_IDX_BITS).
*/

#define SHMMAX 0x2000000 /* max shared seg size (bytes)
*/
/* Try not to change the default shipped SHMMAX - people rely on it */

-------

Hmmmm....

Looks pretty difficult to change.
--
Lamar Owen
WGCR Internet Radio
1 Peter 4:11