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Date:      Thu, 03 May 2001 20:23:35 -0700
From:      John Merryweather Cooper <jmcoopr@webmail.bmi.net>
To:        dpetrou@cs.cmu.edu
Cc:        Antoine.Beaupre@ericsson.ca, freebsd-stable@FreeBSD.ORG
Subject:   Re: Should /sys/i386/conf/GENERIC's SysV shared memory  settings+defaults  be re-thought?
Message-ID:  <3AF220B7.979E8371@webmail.bmi.net>
References:  <20010503221951.G47670@amant.pdl.cs.cmu.edu>

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David Petrou wrote:
> 
> > If I may comment on my desktop experience... I have been running
> > E+gnome, with the usual netscape/xemacs/mailer combination for a good
> > while now, on a Pentium 166Mhz with 32M but around 100-150Mb or swap.
> >
> > Never had problems with SHM.
> 
> i've commented about the problems with shm and a heavy enlightenment /
> gnome load a few weeks ago to stable, but my message was pretty much
> ignored.  also note that this issue has been brought up in current a
> year or so ago.
> 
> my problems went away with:
> 
>   options  SHMMAXPGS=8192
>   options  SHMMNI=4096
>   options  SHMSEG=1024

My settings are quite similar:

# modify SysV parameters to provide more memory for Amanda and
GNOME+Enlightenment
options		SHMMAXPGS=8193	# provides 32 meg of shared memory
options		SHMALL=8193	# provide 8KB + shareable memory
options		SHMMAX="(SHMMAXPGS*PAGE_SIZE+1)"

options		SHMMIN=2	# same as default
options		SHMMNI=257	# maximum shared memory identifiers
options		SHMSEG=65	# max shared memory segments per process

options		SEMMAP=255	# entries in semaphore map
options		SEMMNI=81	# semaphore identifiers in system
options		SEMMNS=481	# semaphores in system
options		SEMMNU=255	# undo structures in system
options		SEMMSL=481	# max semaphores per id
options		SEMOPM=801	# max operations per semop call
options		SEMUME=81	# max undo entries per process

options		MSGMNB=16385	# max characters per message queue
options		MSGMNI=321	# max message queue identifiers
options		MSGSEG=16385	# max message segments in system
options		MSGSSZ=128	# message seg size (2**7)
options		MSGTQL=321	# max messages in system
 
> i don't know enough about the internals to know the downside for using
> these high values, but i'm pretty confident on today's architectures
> it's irrelevant.  can someone that knows more than i confirm this and
> make a permanent change to the kernel config file?  it would spare a
> lot of people some headache.  my symptoms before making this change
> were gnome-terminals disappearing when starting xmms.  not a very
> clear connection to shm.

I don't (yet) either.  But I was purposefully shooting for 32 megs (and
one page more) of shared memory.  I'm going to experiment and see if I
can get by with less.  But this amount works pretty well.

jmc 
> > A.
> 
> david
>

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