Caveat reader: With the exception of procfs stuff in 2.3.x, most of my
VFS participation thus far has been of the "I want to work on this when
I get time" sort of partitication. ;-)
First, my request:
Add an fcntl flag, O_NOCACHE (or O_DIRECT, unimplemented) which allows
an app to hint that it does not want the OS to cache this data. This
will be a _big_ win for servers and desktops where large multimedia or
database files are slung around.
Matthew Wilcox wrote:
> Btree directories (phil)
I hope these are _not_ pure binary search trees but rather a smarter
ADT...
> Backup inode table
interesting idea
> fine-grained locking
al viro was kind enough to e-mail me some of his thoughts on banishing
the big kernel lock from the VFS. Though my time with the VFS has been
nil in the past few months, I'd still like to work on this if noone
beats me to it.
IIRC the two big items are dcache/dentry and inode threading.
> Online defragmentation & size
Has there been any substantive discussion about online defragmentation?
I think it is a wholly separate, and more interesting issue than resize
(which will be solved in the future with LVMs, IMHO...)
For online defrag, there are tons of different scenarios and hueristics
which can be employed to optimize for various situations:
* move frequently-accessed files to the middle of the disk (requires
knowledge of physical disk organization, below the partition layer)
* group files together on disk in directories, with gaps of free space
in between for placement of files "near" other files in the same
directory
* options to pack files into inodes (if possible and supported by fs) or
to fragment small files, to conserve space
* dozens of hueristics. if online defrag is in userspace, admin can
even craft their own disk optimization rules.
Kernel changes.... Short term, the easiest implementation will be
in-kernel. Long term, I would like to see (if possible) a set of
generalized ioctls which allow a userspace program to contain the bulk
of the defragmenting/disk optimization logic.
Any and all ideas for online defrag, please post. I'm very interested.
> delayed allocation
this needs to be in the VFS desperately. every new & advanced
filesystem is winding up implementing their own logic for this...
> Address spaces (viro)
can someone elaborate?
> sort out interface to block devices (viro)
mostly done?
--
Jeff Garzik | Only so many songs can be sung
Building 1024 | with two lips, two lungs, and
MandrakeSoft, Inc. | one tongue.
