Calling verity_verify_io in bh for IO of all sizes is not suitable for
embedded devices. From our tests, it can improve the performance of 4K
synchronise random reads.
For example:
./fio --name=rand_read --ioengine=psync --rw=randread --bs=4K \
--direct=1 --numjobs=8 --runtime=60 --time_based --group_reporting \
--filename=/dev/block/mapper/xx-verity
But it will degrade the performance of 512K synchronise sequential reads
on our devices.
For example:
./fio --name=read --ioengine=psync --rw=read --bs=512K --direct=1 \
--numjobs=8 --runtime=60 --time_based --group_reporting \
--filename=/dev/block/mapper/xx-verity
A parameter array is introduced by this change. And users can modify the
default config by /sys/module/dm_verity/parameters/use_bh_blocks.
The default limits for NONE/RT/BE/IDLE is set to UINT_MAX to keep the
original behaviour.
Signed-off-by: LongPing Wei <weilongping@xxxxxxxx>
---
drivers/md/dm-verity-target.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index e86c1431b108..1e0d0920d6a9 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -30,6 +30,7 @@
#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
+#define DM_VERITY_USE_BH_DEFAULT_BLOCKS UINT_MAX
#define DM_VERITY_MAX_CORRUPTED_ERRS 100
@@ -49,6 +50,15 @@ static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE
module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
+static unsigned int dm_verity_use_bh_blocks[4] = {
+ DM_VERITY_USE_BH_DEFAULT_BLOCKS, // IOPRIO_CLASS_NONE
+ DM_VERITY_USE_BH_DEFAULT_BLOCKS, // IOPRIO_CLASS_RT
+ DM_VERITY_USE_BH_DEFAULT_BLOCKS, // IOPRIO_CLASS_BE
+ DM_VERITY_USE_BH_DEFAULT_BLOCKS // IOPRIO_CLASS_IDLE
+};
+
+module_param_array_named(use_bh_blocks, dm_verity_use_bh_blocks, uint, NULL, 0644);
+
static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled);
/* Is at least one dm-verity instance using ahash_tfm instead of shash_tfm? */
@@ -652,6 +662,12 @@ static void verity_bh_work(struct work_struct *w)
verity_finish_io(io, errno_to_blk_status(err));
}
+static inline bool verity_use_bh(unsigned int n_blocks, unsigned short ioprio)
+{
+ return ioprio <= IOPRIO_CLASS_IDLE &&
+ n_blocks <= READ_ONCE(dm_verity_use_bh_blocks[ioprio]);
+}
+
static void verity_end_io(struct bio *bio)
{
struct dm_verity_io *io = bio->bi_private;
@@ -664,7 +680,8 @@ static void verity_end_io(struct bio *bio)
return;
}
- if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq) {
+ if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq &&
+ verity_use_bh(io->n_blocks, IOPRIO_PRIO_CLASS(bio->bi_ioprio))) {
INIT_WORK(&io->bh_work, verity_bh_work);
queue_work(system_bh_wq, &io->bh_work);
} else {
--
2.34.1
