Thanks for you time.

Tejun Heo wrote on 2021/7/30 1:11 上午:

Hello,

On Wed, Jul 28, 2021 at 05:01:41PM +0800, brookxu wrote:

quoted

diff --git a/block/blk-merge.c b/block/blk-merge.c
index a11b3b5..86ff943 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c

@@ -348,6 +348,8 @@ void __blk_queue_split(struct bio **bio, unsigned int *nr_segs)
 		trace_block_split(split, (*bio)->bi_iter.bi_sector);
 		submit_bio_noacct(*bio);
 		*bio = split;
+
+		blk_throtl_recharge_bio(*bio);

Can you rename this blk_throtl_charge_bio_split()?

Ok, i will do it in next version.

quoted

@@ -524,6 +537,11 @@ static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp,
 	tg->idletime_threshold = DFL_IDLE_THRESHOLD;
 	tg->idletime_threshold_conf = DFL_IDLE_THRESHOLD;
 
+	atomic_set(&tg->io_split_cnt[0], 0);
+	atomic_set(&tg->io_split_cnt[1], 0);
+	atomic_set(&tg->last_io_split_cnt[0], 0);
+	atomic_set(&tg->last_io_split_cnt[1], 0);

We likely don't need these. pd's zeroed on allocation.

Right, i will remove these init code.

quoted

@@ -877,10 +900,19 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)
 	else
 		tg->bytes_disp[rw] = 0;
 
-	if (tg->io_disp[rw] >= io_trim)
+	if (tg_io_disp(tg, rw) >= io_trim) {

Instead of checking this in multiple places, would it be simpler to transfer
the atomic counters to the existing counters whenever we enter blk-throtl
and leave the rest of the code as-is?

If we do this, we need to do similar processing on the bio submission path and the bio
resubmission path in pending_timer. It seems that the code is more complicated?

Thanks.