From: Bart Van Assche <bvanassche@acm.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
Jaegeuk Kim <jaegeuk@kernel.org>,
Bart Van Assche <bvanassche@acm.org>,
Damien Le Moal <damien.lemoal@wdc.com>,
Johannes Thumshirn <johannes.thumshirn@wdc.com>,
Himanshu Madhani <himanshu.madhani@oracle.com>,
Hannes Reinecke <hare@suse.de>, Ming Lei <ming.lei@redhat.com>
Subject: [PATCH 05/14] block/mq-deadline: Add several comments
Date: Tue, 8 Jun 2021 16:06:54 -0700 [thread overview]
Message-ID: <20210608230703.19510-6-bvanassche@acm.org> (raw)
In-Reply-To: <20210608230703.19510-1-bvanassche@acm.org>
Make the code easier to read by adding more comments.
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
block/mq-deadline.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index 8eea2cbf2bf4..31418e9ce9e2 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -139,6 +139,9 @@ static void dd_request_merged(struct request_queue *q, struct request *req,
}
}
+/*
+ * Callback function that is invoked after @next has been merged into @req.
+ */
static void dd_merged_requests(struct request_queue *q, struct request *req,
struct request *next)
{
@@ -375,6 +378,8 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd)
}
/*
+ * Called from blk_mq_run_hw_queue() -> __blk_mq_sched_dispatch_requests().
+ *
* One confusing aspect here is that we get called for a specific
* hardware queue, but we may return a request that is for a
* different hardware queue. This is because mq-deadline has shared
@@ -438,6 +443,10 @@ static int dd_init_queue(struct request_queue *q, struct elevator_type *e)
return 0;
}
+/*
+ * Try to merge @bio into an existing request. If @bio has been merged into
+ * an existing request, store the pointer to that request into *@rq.
+ */
static int dd_request_merge(struct request_queue *q, struct request **rq,
struct bio *bio)
{
@@ -461,6 +470,10 @@ static int dd_request_merge(struct request_queue *q, struct request **rq,
return ELEVATOR_NO_MERGE;
}
+/*
+ * Attempt to merge a bio into an existing request. This function is called
+ * before @bio is associated with a request.
+ */
static bool dd_bio_merge(struct request_queue *q, struct bio *bio,
unsigned int nr_segs)
{
@@ -518,6 +531,9 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
}
}
+/*
+ * Called from blk_mq_sched_insert_request() or blk_mq_sched_insert_requests().
+ */
static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
struct list_head *list, bool at_head)
{
@@ -544,6 +560,8 @@ static void dd_prepare_request(struct request *rq)
}
/*
+ * Callback from inside blk_mq_free_request().
+ *
* For zoned block devices, write unlock the target zone of
* completed write requests. Do this while holding the zone lock
* spinlock so that the zone is never unlocked while deadline_fifo_request()
next prev parent reply other threads:[~2021-06-08 23:07 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-08 23:06 [PATCH 00/14] Improve I/O priority support Bart Van Assche
2021-06-08 23:06 ` [PATCH 01/14] block/Kconfig: Make the BLK_WBT and BLK_WBT_MQ entries consecutive Bart Van Assche
2021-06-09 4:14 ` Damien Le Moal
2021-06-09 7:03 ` Johannes Thumshirn
2021-06-10 6:02 ` Hannes Reinecke
2021-06-08 23:06 ` [PATCH 02/14] block/blk-cgroup: Swap the blk_throtl_init() and blk_iolatency_init() calls Bart Van Assche
2021-06-09 4:19 ` Damien Le Moal
2021-06-09 7:05 ` Johannes Thumshirn
2021-06-10 6:02 ` Hannes Reinecke
2021-06-08 23:06 ` [PATCH 03/14] block/blk-rq-qos: Move a function from a header file into a C file Bart Van Assche
2021-06-09 4:22 ` Damien Le Moal
2021-06-10 6:03 ` Hannes Reinecke
2021-06-08 23:06 ` [PATCH 04/14] block: Introduce the ioprio rq-qos policy Bart Van Assche
2021-06-09 4:40 ` Damien Le Moal
2021-06-09 16:48 ` Bart Van Assche
2021-06-10 0:29 ` Damien Le Moal
2021-06-10 6:20 ` Hannes Reinecke
2021-06-10 17:14 ` Bart Van Assche
2021-06-08 23:06 ` Bart Van Assche [this message]
2021-06-10 6:21 ` [PATCH 05/14] block/mq-deadline: Add several comments Hannes Reinecke
2021-06-08 23:06 ` [PATCH 06/14] block/mq-deadline: Add two lockdep_assert_held() statements Bart Van Assche
2021-06-10 6:21 ` Hannes Reinecke
2021-06-08 23:06 ` [PATCH 07/14] block/mq-deadline: Remove two local variables Bart Van Assche
2021-06-10 6:22 ` Hannes Reinecke
2021-06-08 23:06 ` [PATCH 08/14] block/mq-deadline: Rename dd_init_queue() and dd_exit_queue() Bart Van Assche
2021-06-08 23:06 ` [PATCH 09/14] block/mq-deadline: Improve compile-time argument checking Bart Van Assche
2021-06-08 23:06 ` [PATCH 10/14] block/mq-deadline: Improve the sysfs show and store macros Bart Van Assche
2021-06-09 4:46 ` Damien Le Moal
2021-06-09 16:54 ` Bart Van Assche
2021-06-10 0:31 ` Damien Le Moal
2021-06-09 7:11 ` Johannes Thumshirn
2021-06-09 16:59 ` Bart Van Assche
2021-06-10 6:23 ` Hannes Reinecke
2021-06-08 23:07 ` [PATCH 11/14] block/mq-deadline: Reserve 25% of scheduler tags for synchronous requests Bart Van Assche
2021-06-10 6:26 ` Hannes Reinecke
2021-06-08 23:07 ` [PATCH 12/14] block/mq-deadline: Add I/O priority support Bart Van Assche
2021-06-09 5:03 ` Damien Le Moal
2021-06-09 17:25 ` Bart Van Assche
2021-06-10 0:39 ` Damien Le Moal
2021-06-10 6:35 ` Hannes Reinecke
2021-06-08 23:07 ` [PATCH 13/14] block/mq-deadline: Add cgroup support Bart Van Assche
2021-06-10 6:37 ` Hannes Reinecke
2021-06-08 23:07 ` [PATCH 14/14] block/mq-deadline: Prioritize high-priority requests Bart Van Assche
2021-06-09 5:10 ` Damien Le Moal
2021-06-10 6:43 ` Hannes Reinecke
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