On 10/18/23 11:00, Bart Van Assche wrote:
-/*
- * For shared tag users, we track the number of currently active users
- * and attempt to provide a fair share of the tag depth for each of them.
- */
-static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,
- struct sbitmap_queue *bt)
-{
- unsigned int depth, users;
-
- if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED))
- return true;
-
- /*
- * Don't try dividing an ant
- */
- if (bt->sb.depth == 1)
- return true;
-
- if (blk_mq_is_shared_tags(hctx->flags)) {
- struct request_queue *q = hctx->queue;
-
- if (!test_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags))
- return true;
- } else {
- if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
- return true;
- }
-
- users = READ_ONCE(hctx->tags->active_queues);
- if (!users)
- return true;
-
- /*
- * Allow at least some tags
- */
- depth = max((bt->sb.depth + users - 1) / users, 4U);
- return __blk_mq_active_requests(hctx) < depth;
-}
(replying to my own email)
Hi Jens,
Do you perhaps remember why the above code was introduced by commit
0d2602ca30e4 ("blk-mq: improve support for shared tags maps") in 2014
(nine years ago)?
Thanks,
Bart.
