brd: use XArray instead of radix-tree to index backing pages

XArray was introduced to hold large array of pointers with a simple API.
XArray API also provides array semantics which simplifies the way we store
and access the backing pages, and the code becomes significantly easier
to understand.

No performance difference was noticed between the two implementation
using fio with direct=1 [1].

[1] Performance in KIOPS:

          |  radix-tree |    XArray  |   Diff
          |             |            |
write     |    315      |     313    |   -0.6%
randwrite |    286      |     290    |   +1.3%
read      |    330      |     335    |   +1.5%
randread  |    309      |     312    |   +0.9%

Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20230511121544.111648-1-p.raghav@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pankaj Raghav 2023-05-11 14:15:44 +02:00 • committed by Jens Axboe
commit 786bb02458