Subject: Re: increasing share memory
To: Giles Lean <>
From: Perry E. Metzger <>
List: netbsd-users
Date: 03/03/2002 16:59:40
In fact, the number in question only gives a maximum to the size of
the sysv shared memory -- since the shared memory is pageable and
handled by the same mechanisms as mmapped shared memory etc. the limit
is really an artifact of the past and should be eliminated.


Giles Lean <> writes:

> > >   options 	SHMMAXPGS=3D32768	# 1024 pages is the default
> > 
> > Which are the advantadges of doing this?
> If your applications need or want more shared memory this is the way
> to give it to them.
> Databases can be quite greedy for shared memory but may not use the
> buffer cache efficiently, so allocating less memory to buffer cache
> and more to shared memory is a win sometimes.  Like all performance
> questions it's highly subject to OS, application, and workload. :-)
> Regards,
> Giles

Perry E. Metzger
NetBSD Development, Support & CDs.