On 01/09/2015 02:40 PM, Mike Snitzer wrote:
On Fri, Jan 09 2015 at 4:11pm -0500,
Jens Axboe <axboe@xxxxxxxxx> wrote:
Actually, try this one instead, it should be a bit more precise than
the first.
Thanks for the test patch.
I'm still seeing failures that look wrong (last_tag=127 could be edge
condition not handled properly?):
[ 14.254632] __bt_get: values before for loop: last_tag=127, index=3
[ 14.255841] __bt_get: values after for loop: last_tag=64, index=2
[ 14.257036]
[ 14.257036] bt_get: __bt_get() returned -1
[ 14.258051] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5
[ 14.259246] nr_free=128, nr_reserved=0
[ 14.259963] active_queues=0
[ 213.115997] __bt_get: values before for loop: last_tag=127, index=3
[ 213.117115] __bt_get: values after for loop: last_tag=96, index=3
[ 213.118200]
[ 213.118200] bt_get: __bt_get() returned -1
[ 213.121593] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5
[ 213.123960] nr_free=128, nr_reserved=0
[ 213.125880] active_queues=0
[ 239.158079] __bt_get: values before for loop: last_tag=8, index=0
[ 239.160363] __bt_get: values after for loop: last_tag=0, index=0
[ 239.162896]
[ 239.162896] bt_get: __bt_get() returned -1
[ 239.166284] queue_num=0, nr_tags=128, reserved_tags=0, bits_per_word=5
[ 239.168623] nr_free=127, nr_reserved=0
[ 239.170508] active_queues=0
Thanks for testing, can you try this one?
--
Jens Axboe
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 60c9d4a93fe4..4130c2bdc6c0 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -143,28 +143,31 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,
static int __bt_get_word(struct blk_align_bitmap *bm, unsigned int last_tag)
{
int tag, org_last_tag, end;
- bool wrap = last_tag != 0;
org_last_tag = last_tag;
end = bm->depth;
- do {
-restart:
- tag = find_next_zero_bit(&bm->word, end, last_tag);
+ while (1) {
+ tag = find_next_zero_bit(&bm->word, bm->depth, last_tag);
if (unlikely(tag >= end)) {
/*
* We started with an offset, start from 0 to
* exhaust the map.
*/
- if (wrap) {
- wrap = false;
+ if (org_last_tag) {
end = org_last_tag;
- last_tag = 0;
- goto restart;
+ last_tag = org_last_tag = 0;
+ continue;
}
return -1;
}
+
+ if (!test_and_set_bit(tag, &bm->word))
+ break;
+
last_tag = tag + 1;
- } while (test_and_set_bit(tag, &bm->word));
+ if (last_tag >= bm->depth - 1)
+ last_tag = 0;
+ }
return tag;
}
@@ -199,9 +202,13 @@ static int __bt_get(struct blk_mq_hw_ctx *hctx, struct blk_mq_bitmap_tags *bt,
goto done;
}
- last_tag = 0;
- if (++index >= bt->map_nr)
+ index++;
+ last_tag = (index << bt->bits_per_word);
+
+ if (index >= bt->map_nr) {
index = 0;
+ last_tag = 0;
+ }
}
*tag_cache = 0;
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
