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From: Luigi Rizzo <luigi@labinfo.iet.unipi.it>
Message-Id: <199707100826.KAA05398@labinfo.iet.unipi.it>
Subject: Re: no SYSVSHM in GENERIC now..
To: joerg_wunsch@uriah.heep.sax.de
Date: Thu, 10 Jul 1997 10:26:44 +0200 (MET DST)
Cc: hackers@FreeBSD.ORG
In-Reply-To: <19970710092221.JN34121@uriah.heep.sax.de> from "J Wunsch" at Jul 10, 97 09:22:02 am
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> As Andrew Atrens wrote:
> 
> > Does the X-server run any faster with MIT-SHM than without?
> 
> No, it doesn't.  The only thing is that it disables the MIT-SHM
> extension if no SYSVSHM is available in the kernel (it catches SIGSYS,
> and attempts to issue a shmget() call).
> 
> MIT-SHM is an extension that must be explicitly used by the clients,
> and AFAIK only few clients actually use it.  It is not to be confused

"tv" and friends seem to run a bit faster with MITSHM since they
probably save one copy. Of course it is much faster to let the
frame grabber dump data straight to the video card.

	Cheers
	Luigi