Date: Wed, 18 Apr 2001 20:53:18 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Matt Dillon <dillon@earth.backplane.com> Cc: Julian Elischer <julian@elischer.org>, Robert Watson <rwatson@FreeBSD.ORG>, Kirk McKusick <mckusick@mckusick.com>, Rik van Riel <riel@conectiva.com.br>, freebsd-hackers@FreeBSD.ORG, David Xu <bsddiy@21cn.com> Subject: Re: vm balance Message-ID: <42362.987619998@critter> In-Reply-To: Your message of "Wed, 18 Apr 2001 11:11:19 PDT." <200104181811.f3IIBJp25644@earth.backplane.com>
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In message <200104181811.f3IIBJp25644@earth.backplane.com>, Matt Dillon writes: > Actually, all this talk does imply that VM objects should be independant > of vnodes. Devices may need to mmap (requiring a VM object), but > don't need all the baggage of a vnode. Julian is absolutely correct > there. Well, you have other VM Objects which doesn't map to vnodes: swap backed anonymous objects for instance. > We do need to guarentee locking order, which means that all I/O > operations should be consistent. If a device or vnode is mmap()able, > then all read, write, and truncation(/extention) ops *should* run > through the VM object first: We guarantee that today my mapping the actual hardware and my having all read/writes be synchronouse. I remember at least one other UNIX which didn't make that guarantee. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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