Date: 03 Nov 2000 11:57:58 -0500 From: Randell Jesup <rjesup@wgate.com> To: Marius Bendiksen <mbendiks@eunet.no> Cc: Alfred Perlstein <bright@wintelcom.net>, Matt Dillon <dillon@earth.backplane.com>, Randell Jesup <rjesup@wgate.com>, arch@FreeBSD.ORG Subject: Re: Like to commit my diskprep Message-ID: <ybulmv1802x.fsf@jesup.eng.tvol.net.jesup.eng.tvol.net> In-Reply-To: Marius Bendiksen's message of "Thu, 2 Nov 2000 23:29:03 %2B0100 (CET)" References: <Pine.BSF.4.05.10011022322581.13327-100000@login-1.eunet.no>
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Marius Bendiksen <mbendiks@eunet.no> writes:
>Actually, block indirection could be fixed by raping the code to support
>the notion of extents. As to allocating in the general locality of the
>inode or datablock, that would require you to be within a distance of 1
>track, and on a system with better things to spend its cache on than
>indirect blocks, you'll lose some when you hit double or triple indirect,
>especially with random access.
1 track? Not really. Modern drives have internal caches and
generally aggressively read-ahead. There was an interesting paper in
SIGOS (I think) around a year ago about inode locality, forward placement,
and storing small files in the inode, and how all of this interacted
with modern drives. Also, what is a "track" on a modern drive? ;-)
>As a side note, I've thought about abusing the actual inodes themselves to
>hold single indirect blocks. Opinions, apart from the general evilness of
>abusing the structures in such a fashion?
That sounds good.
>> Yes, patches would be nice. :)
>
>Patches cannot be formed until a general consensus exists on how the
>patches should do things if and when an enterprising soul made them.
>Otherwise, they stand a good chance at being rejected based on some,
>possibly relevant, objection to how they work.
>
>Also, such patches are likely best formed by the same people that are
>currently suggesting doing a variety of other things for disklabel and
>friends.
I'm willing to help on this, though my time may be limited. I have
_extensive_ FS experience from my Amiga days, and also was the primary
disk-driver person and SCSI expert, and also did "archive" filesystems for
Scala. I've never hacked the internals of ufs, however, but I do know the
issues.
--
Randell Jesup, Worldgate Communications, ex-Scala, ex-Amiga OS team ('88-94)
rjesup@wgate.com
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