linux-kernel - Re: [PATCH RFC 1/3] block/mq-deadline: Revert "block/mq-deadline: Fix the tag reservation code"

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Message-ID: <6e384b29-50d2-64bd-0d08-fc0f086c1cbd@huaweicloud.com>
Date: Tue, 10 Dec 2024 09:50:04 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Bart Van Assche <bvanassche@....org>, Yu Kuai <yukuai1@...weicloud.com>,
 axboe@...nel.dk, akpm@...ux-foundation.org, yang.yang@...o.com,
 ming.lei@...hat.com, osandov@...com, paolo.valente@...aro.org
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
 yi.zhang@...wei.com, yangerkun@...wei.com, "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH RFC 1/3] block/mq-deadline: Revert "block/mq-deadline: Fix
 the tag reservation code"

Hi,

在 2024/12/10 2:02, Bart Van Assche 写道:
> This is not correct. dd->async_depth can be modified via sysfs.

How about the following patch to fix min_shallow_depth for deadline?

Thanks,
Kuai

diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index a9cf8e19f9d1..040ebb0b192d 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -667,8 +667,7 @@ static void dd_depth_updated(struct blk_mq_hw_ctx *hctx)
         struct blk_mq_tags *tags = hctx->sched_tags;

         dd->async_depth = q->nr_requests;
-
-       sbitmap_queue_min_shallow_depth(&tags->bitmap_tags, 1);
+       sbitmap_queue_min_shallow_depth(&tags->bitmap_tags, 
dd->async_depth);
  }

  /* Called by blk_mq_init_hctx() and blk_mq_init_sched(). */
@@ -1012,6 +1011,47 @@ SHOW_INT(deadline_fifo_batch_show, dd->fifo_batch);
  #undef SHOW_INT
  #undef SHOW_JIFFIES

+static ssize_t deadline_async_depth_store(struct elevator_queue *e,
+                                         const char *page, size_t count)
+{
+       struct deadline_data *dd = e->elevator_data;
+       struct request_queue *q = dd->q;
+       struct blk_mq_hw_ctx *hctx;
+       unsigned long i;
+       int v;
+       int ret = kstrtoint(page, 0, &v);
+
+       if (ret < 0)
+               return ret;
+
+       if (v < 1)
+               v = 1;
+       else if (v > dd->q->nr_requests)
+               v = dd->q->nr_requests;
+
+       if (v == dd->async_depth)
+               return count;
+
+       blk_mq_freeze_queue(q);
+       blk_mq_quiesce_queue(q);
+
+       dd->async_depth = v;
+       if (blk_mq_is_shared_tags(q->tag_set->flags)) {
+               sbitmap_queue_min_shallow_depth(
+                       &q->sched_shared_tags->bitmap_tags, 
dd->async_depth);
+       } else {
+               queue_for_each_hw_ctx(q, hctx, i)
+                       sbitmap_queue_min_shallow_depth(
+                               &hctx->sched_tags->bitmap_tags,
+                               dd->async_depth);
+       }
+
+       blk_mq_unquiesce_queue(q);
+       blk_mq_unfreeze_queue(q);
+
+       return count;
+}
+
  #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) 
         \
  static ssize_t __FUNC(struct elevator_queue *e, const char *page, 
size_t count)        \
  {                                                                      \
@@ -1037,7 +1077,6 @@ STORE_JIFFIES(deadline_write_expire_store, 
&dd->fifo_expire[DD_WRITE], 0, INT_MA
  STORE_JIFFIES(deadline_prio_aging_expire_store, 
&dd->prio_aging_expire, 0, INT_MAX);
  STORE_INT(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, 
INT_MAX);
  STORE_INT(deadline_front_merges_store, &dd->front_merges, 0, 1);
-STORE_INT(deadline_async_depth_store, &dd->async_depth, 1, INT_MAX);
  STORE_INT(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX);
  #undef STORE_FUNCTION
  #undef STORE_INT