Date: 14 Jul 1999 08:22:03 -0700 From: cgd@netbsd.org (Chris G. Demetriou) To: Doug Rabson <dfr@nlsystems.com> Cc: Jon Ribbens <jon@oaktree.co.uk>, Alfred Perlstein <bright@rush.net>, "Daniel C. Sobral" <dcs@newsguy.com>, freebsd-hackers@freebsd.org, tech-userlevel@netbsd.org, tech@openbsd.org Subject: Re: Replacement for grep(1) (part 2) Message-ID: <87oghfz278.fsf@redmail.redback.com> In-Reply-To: Doug Rabson's message of Wed, 14 Jul 1999 08:31:07 %2B0100 (BST) References: <Pine.BSF.4.10.9907140829520.58023-100000@salmon.nlsystems.com>
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Doug Rabson <dfr@nlsystems.com> writes: > Overcommit can be used for many reasons. I use it to reserve a large > linear address space to mmap alpha i/o spaces [...] Overcommit can be used for many reasons, but unless you've misdescribed what you're doing, _that's not one of them_. The mapped I/O pages need no backing store to be allocated for them by the VM system. They're backed by hardware. And if you have 'placeholder' pages (I note that you didn't say you mmap all of alpha i/o space, just reserve a large linear address space in which to mmap it), then it should be possible to map them in such a way (e.g. read-only ZFOD) in which they wouldn't count against backing store requirements, either. cgd -- Chris Demetriou - cgd@netbsd.org - http://www.netbsd.org/People/Pages/cgd.html Disclaimer: Not speaking for NetBSD, just expressing my own opinion. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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