On 2019/02/27 5:38, yuyufen wrote:

On 2019/2/27 18:27, Marcos Paulo de Souza wrote:

quoted

Hello Yufen,

On 2/27/19 3:21 AM, Yufen Yu wrote:

quoted

For q->poll_nsec == -1, means using classic poll, not hybrid poll.
We introduce a new flag BLK_POLL_DELAY_INVALID to replace -1, which
may make code much easier to read.

In the commit message you say BLK_POLL_DELAY_INVALID, but the code and 
the commit title use BLK_MQ_POLL_HYBRID_INVALID. Is this a typo?

Thanks a lot for pointing out this fault. What I want to
say is BLK_MQ_POLL_HYBRID_INVALID, not BLK_POLL_DELAY_INVALID.

Yufen
Thanks

quoted

Thanks.

quoted

Signed-off-by: Yufen Yu <redacted>
---
  block/blk-mq.c         | 4 ++--
  block/blk-sysfs.c      | 4 ++--
  include/linux/blkdev.h | 3 +++
  3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9437a5eb07cf..8df9f6e97d2e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c

@@ -2857,7 +2857,7 @@ struct request_queue 

*blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
      /*
       * Default to classic polling
       */
-    q->poll_nsec = -1;
+    q->poll_nsec = BLK_MQ_POLL_HYBRID_INVALID;
        blk_mq_init_cpu_queues(q, set->nr_hw_queues);
      blk_mq_add_queue_tag_set(set, q);

@@ -3389,7 +3389,7 @@ static bool blk_mq_poll_hybrid(struct 

request_queue *q,
  {
      struct request *rq;
  -    if (q->poll_nsec == -1)
+    if (q->poll_nsec == BLK_MQ_POLL_HYBRID_INVALID)
          return false;
        if (!blk_qc_t_is_internal(cookie))

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 590d1ef2f961..8775b898f96d 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c

@@ -360,7 +360,7 @@ static ssize_t queue_poll_delay_show(struct 

request_queue *q, char *page)
  {
      int val;
  -    if (q->poll_nsec == -1)
+    if (q->poll_nsec == BLK_MQ_POLL_HYBRID_INVALID)
          val = -1;
      else
          val = q->poll_nsec / 1000;

@@ -381,7 +381,7 @@ static ssize_t queue_poll_delay_store(struct 

request_queue *q, const char *page,
          return err;
        if (val == -1)
-        q->poll_nsec = -1;
+        q->poll_nsec = BLK_MQ_POLL_HYBRID_INVALID;
      else
          q->poll_nsec = val * 1000;
  diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 338604dff7d0..2102447b67d9 100644

--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h

@@ -50,6 +50,9 @@ struct blk_stat_callback;
  /* Must be consistent with blk_mq_poll_stats_bkt() */
  #define BLK_MQ_POLL_STATS_BKTS 16
  +/* Using default classic polling */
+#define BLK_MQ_POLL_HYBRID_INVALID -1

May be simply renaming this as BLK_MQ_POLL_CLASSIC would be even simpler ?
That matches the comment and also the actual use of the macro, i.e.:

if (q->poll_nsec == -1)

means "do classic polling", which would nicely fits with:

if (q->poll_nsec == BLK_MQ_POLL_CLASSIC)

A lot easier to understand in my opinion. Using BLK_MQ_POLL_HYBRID_INVALID as a
name is confusing with potential error cases where we actually want to do hybrid
polling but the poll sleep time is invalid.

quoted

quoted

+
  /*
   * Maximum number of blkcg policies allowed to be registered 
concurrently.
   * Defined here to simplify include dependency.

.

-- 
Damien Le Moal
Western Digital Research