DragonFly kernel List (threaded) for 2009-06
Re: HAMMER changes in HEAD, also needs testing
Matthew Dillon schrieb:
I've made some fairly straightforward changes to HAMMER in HEAD, but
they need testing.
* Inode numbers are now allocated to maintain linearity with the
directory scan order, when possible. Note however that this
optimization breaks if a file is created under a temporary name
and then renamed.
This should significantly improve cpdup, tar, cpio, ls, and find.
The optimization only applies to newly created directory trees,
existing trees cannot be reoptimized since their inode numbers
have already been assigned.
Would be great to have some numbers here, how this and the modifications
to cpdup changes performance.
* Hints can now be passed to the block allocator. The B-Tree code
now uses them to try to keep internal nodes more localized. The
block allocator also now leaves a bit of empty space at the end
of the big-block for localized B-Tree expansion room.
I am trying to understand the hinting mechanism. So before this commit,
B-Tree nodes were always allocated physical linearly out of a big block,
while after this commit, you pass a hint, where the B-Tree node could or
should physically be placed within a big-block, and if that space is not
yet allocated, the B-Tree is allocated at the hinted position. If the
hinted position is already allocated, you simply fall back to linear
allocation. That is how I understand it. I do not know how you calculate