btrfs: use a kmem_cache for block groups

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We are currently allocating block groups using the generic slabs, and
given that the size of btrfs_block_group structure is 672 bytes (on a
release kernel), we end up using the kmalloc-1024 slab and therefore
waste quite some memory since on a 4K page system we can only fit 4
block groups per page. The block groups are also allocated and
delallocated with some frequency, specially if we have auto reclaim
enabled.

So use a kmem_cache for block groups, this way on a 4K page system we
can fit 6 block groups per page instead of 4.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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Filipe Manana 2026-04-15 12:26:40 +01:00 • committed by David Sterba

parent 3fc0803f1c

commit d293344c22

3 changed files with 26 additions and 3 deletions

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23

fs/btrfs/block-group.c

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3

fs/btrfs/block-group.h

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3

fs/btrfs/super.c

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