Messages in this thread | | | Date | Wed, 01 May 2002 14:38:37 -0700 | From | Andrew Morton <> | Subject | Re: [STATUS 2.5] May 1, 2002 |
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Mike Fedyk wrote: > > On Wed, May 01, 2002 at 09:53:37AM -0400, Guillaume Boissiere wrote: > > new framebuffer layer, as well as some more delayed disk block > > allocation bits. > > Actually Andrews work on address_space based writeback is related somewhat, > but really it's a rewrite/cleanup of the buffer layer. Delayed block > alocation is helped alot by this, and almost depends on it IIRC. > > One vote for a seperate listing in the status for "Address Space based > Writeback / Buffer layer cleanup".
Well the next major step here is going direct pagecache<->BIO, bypassing the intermediate submit_bh for most I/O.
Probably that will make most of the performance benefits of delayed-allocate go away.
There are other reasons for implementing delalloc (XFS, improved layout, ...). So it ain't dead yet.
At 48 bytes, 2.5's buffer_head is now precisely half the size of 2.4's. I'm hoping to be able to shed another eight bytes yet.
With the pagecache<->BIO change, the buffer_head will most definitely become "per-page metadata which describes the state of sub-page segments" and not "something which is used for performing I/O".
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