Date: Thu, 11 Mar 2004 08:17:17 +0100 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Colin Percival <colin.percival@wadham.ox.ac.uk> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/sys mdioctl.h src/sys/dev/md md.c src/sbin/mdconfig mdconfig.8 mdconfig.c Message-ID: <48493.1078989437@critter.freebsd.dk> In-Reply-To: Your message of "Thu, 11 Mar 2004 06:41:06 GMT." <6.0.1.1.1.20040311063721.03e220b8@imap.sfu.ca>
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In message <6.0.1.1.1.20040311063721.03e220b8@imap.sfu.ca>, Colin Percival writ es: >At 06:35 11/03/2004, Poul-Henning Kamp wrote: >>In message <6.0.1.1.1.20040311062306.03f9ade0@imap.sfu.ca>, Colin Percival >>writ >>es: >> ><kernelnewbie> >> > Is it really necessary for vnode-backed memory disks to be >> >accessed through the filesystem? Why can't md(4) hijack the >> >disk blocks which constitute the file (telling the filesystem >> >not to touch them, of course) and translate I/O operations >> >directly into I/O on the underlying device? >> ></kernelnewbie> >> >>That would be a really complex solution to a problem which should not >>exist in the first place :-) > > Well... yes, but it *would* make sure that data didn't get passed >back up to the filesystem layer. And it would probably be faster, >which is why I thought of it. This is all true, but as I said, IMO the benefits does not outweigh the added complexity. -- 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.
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