Zach Brown dcef9c0ada scoutfs: store the buddy allocator in a radix ...

The current implementation of the allocator was built for for a world
where blocks were much, much, larger.  It could get away with keeping
the entire bitmap resident and having to read it its entirety before
being able to use it for the first time.

That will not work in the current architecture that's built around a
smaller metadata block size.  The raw size of the allocator gets large
enough that all of those behaviours become problematic at scale.

This shifts the buddy allocator to be stored in a radix of blocks
instead of in a ring log.  This brings it more in line with the
structure of the btree item indexes.  It can be initially read, cached,
and invalidated at block granularity.

In addition, it cleverly uses the cow block structures to solve the
unreferenced space allocation constraint that the previous allocator
hadn't.  It can compare the dirty and stable blocks to discover free
blocks that aren't referenced by the old stable state.  The old
allocator would have grown a bunch of extra special complexity to
address this.

There's still work to be done but this is a solid start.

Signed-off-by: Zach Brown <zab@versity.com>

2016-07-27 12:09:29 -07:00

..

src

scoutfs: store the buddy allocator in a radix

2016-07-27 12:09:29 -07:00

.gitignore

scoutfs: add cscope noise to .gitignore

2016-04-12 19:37:31 -07:00

Makefile

scoutfs: require sparse builds

2016-03-24 21:45:08 -07:00