btrfs: cache folio size and shift in extent_buffer

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After the conversion to folio interfaces (but without the patch to
enable larger folio allocation), there is an LTP report about observable
performance drop on metadata heavy operations.

https://lore.kernel.org/linux-btrfs/202312221750.571925bd-oliver.sang@intel.com/

This drop is caused by the extra code of calculating the
folio_size()/folio_shift(), instead of the old hard coded
PAGE_SIZE/PAGE_SHIFT.

To slightly reduce the overhead, just cache both folio_size and
folio_shift in extent_buffer.

The two new members (u32 folio_size and u8 folio_shift) are stored
inside the holes of extent_buffer. folio_size is shared with len, which
is reduced to u32. The size of eb does not change.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

...

This commit is contained in:

Qu Wenruo 2024-01-05 16:05:55 +10:30 • committed by David Sterba

parent 4d02b54390

commit 84cda1a608

5 changed files with 42 additions and 28 deletions

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12

fs/btrfs/accessors.c

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2

fs/btrfs/ctree.c

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2

fs/btrfs/disk-io.c

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38

fs/btrfs/extent_io.c

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16

fs/btrfs/extent_io.h

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