If our shallow depth is smaller than the wake batching of sbitmap, we can introduce hangs. Ensure that sbitmap knows how low we'll go.
Acked-by: Paolo Valente <[email protected]> Signed-off-by: Jens Axboe <[email protected]> --- block/bfq-iosched.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 10294124d597..b622e73a326a 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -5081,10 +5081,13 @@ void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg) /* * See the comments on bfq_limit_depth for the purpose of - * the depths set in the function. + * the depths set in the function. Return minimum shallow depth we'll use. */ -static void bfq_update_depths(struct bfq_data *bfqd, struct sbitmap_queue *bt) +static unsigned int bfq_update_depths(struct bfq_data *bfqd, + struct sbitmap_queue *bt) { + unsigned int i, j, min_shallow = UINT_MAX; + /* * In-word depths if no bfq_queue is being weight-raised: * leaving 25% of tags only for sync reads. @@ -5115,14 +5118,22 @@ static void bfq_update_depths(struct bfq_data *bfqd, struct sbitmap_queue *bt) bfqd->word_depths[1][0] = max(((1U << bt->sb.shift) * 3) >> 4, 1U); /* no more than ~37% of tags for sync writes (~20% extra tags) */ bfqd->word_depths[1][1] = max(((1U << bt->sb.shift) * 6) >> 4, 1U); + + for (i = 0; i < 2; i++) + for (j = 0; j < 2; j++) + min_shallow = min(min_shallow, bfqd->word_depths[i][j]); + + return min_shallow; } static int bfq_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int index) { struct bfq_data *bfqd = hctx->queue->elevator->elevator_data; struct blk_mq_tags *tags = hctx->sched_tags; + unsigned int min_shallow; - bfq_update_depths(bfqd, &tags->bitmap_tags); + min_shallow = bfq_update_depths(bfqd, &tags->bitmap_tags); + sbitmap_queue_min_shallow_depth(&tags->bitmap_tags, min_shallow); return 0; } -- 2.7.4
