From owner-freebsd-hackers Wed Jul 14 8:23:11 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from mail.netbsd.org (redmail.netbsd.org [155.53.200.193]) by hub.freebsd.org (Postfix) with SMTP id A47ED14C2F for ; Wed, 14 Jul 1999 08:23:08 -0700 (PDT) (envelope-from cgd@netbsd.org) Received: (qmail 23473 invoked by uid 1000); 14 Jul 1999 15:22:04 -0000 To: Doug Rabson Cc: Jon Ribbens , Alfred Perlstein , "Daniel C. Sobral" , freebsd-hackers@freebsd.org, tech-userlevel@netbsd.org, tech@openbsd.org Subject: Re: Replacement for grep(1) (part 2) References: From: cgd@netbsd.org (Chris G. Demetriou) Date: 14 Jul 1999 08:22:03 -0700 In-Reply-To: Doug Rabson's message of Wed, 14 Jul 1999 08:31:07 +0100 (BST) Message-ID: <87oghfz278.fsf@redmail.redback.com> Lines: 22 X-Mailer: Gnus v5.5/Emacs 20.2 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Doug Rabson 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