Path: utzoo!attcan!uunet!auspex!guy
From: guy@auspex.UUCP (Guy Harris)
Newsgroups: comp.unix.wizards
Subject: Re: Shared memory
Keywords: shared, memory, non-swappable
Message-ID: <491@auspex.UUCP>
Date: 22 Nov 88 21:05:12 GMT
References: <22739@cci632.UUCP>
Reply-To: guy@auspex.UUCP (Guy Harris)
Organization: Auspex Systems, Santa Clara
Lines: 11

>Does anyone know if non-swappable shared memory is supported by
>System V? I need to know because some of our applications developers
>want it. Our sister division in California supports it, but I cannot
>find documentation for it in the SVID.

It's not in the SVID, but some versions of System V have (privileged!)
SHM_LOCK and SHM_UNLOCK "shmctl" operations that lock shared memory
segments into memory.  There is otherwise no guarantee that shared
memory segments are non-swappable; some older implementations happen to
lock them in memory, but other ones (more recent ones, generally) do
not.