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Subject[PATCH 2/2] blk-mq: save default hctx into ctx->hctxs for not-supported type
Date
Currently, we check whether the hctx type is supported every time
in hot path. Actually, this is not necessary, we could save the
default hctx into ctx->hctxs if the type is not supported when
map swqueues and use it directly with ctx->hctxs[type].

We also needn't check whether the poll is enabled or not, because
the caller would clear the REQ_HIPRI in that case.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
---
block/blk-mq.c | 9 ++++++++-
block/blk-mq.h | 15 ++++++---------
2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 6898d24..1dab467 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2430,8 +2430,11 @@ static void blk_mq_map_swqueue(struct request_queue *q)

ctx = per_cpu_ptr(q->queue_ctx, i);
for (j = 0; j < set->nr_maps; j++) {
- if (!set->map[j].nr_queues)
+ if (!set->map[j].nr_queues) {
+ ctx->hctxs[j] = blk_mq_map_queue_type(q,
+ HCTX_TYPE_DEFAULT, i);
continue;
+ }

hctx = blk_mq_map_queue_type(q, j, i);
ctx->hctxs[j] = hctx;
@@ -2454,6 +2457,10 @@ static void blk_mq_map_swqueue(struct request_queue *q)
*/
BUG_ON(!hctx->nr_ctx);
}
+
+ for (; j < HCTX_MAX_TYPES; j++)
+ ctx->hctxs[j] = blk_mq_map_queue_type(q,
+ HCTX_TYPE_DEFAULT, i);
}

mutex_unlock(&q->sysfs_lock);
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 998f5cf..ed1ed45 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -98,7 +98,7 @@ static inline struct blk_mq_hw_ctx *blk_mq_map_queue_type(struct request_queue *
* blk_mq_map_queue() - map (cmd_flags,type) to hardware queue
* @q: request queue
* @flags: request command flags
- * @cpu: CPU
+ * @ctx: mq cpu ctx
*/
static inline struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q,
unsigned int flags,
@@ -106,15 +106,12 @@ static inline struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q,
{
enum hctx_type type = HCTX_TYPE_DEFAULT;

- if ((flags & REQ_HIPRI) &&
- q->tag_set->nr_maps > HCTX_TYPE_POLL &&
- q->tag_set->map[HCTX_TYPE_POLL].nr_queues &&
- test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+ /*
+ * The caller ensure that if REQ_HIPRI, poll must be enabled.
+ */
+ if (flags & REQ_HIPRI)
type = HCTX_TYPE_POLL;
-
- else if (((flags & REQ_OP_MASK) == REQ_OP_READ) &&
- q->tag_set->nr_maps > HCTX_TYPE_READ &&
- q->tag_set->map[HCTX_TYPE_READ].nr_queues)
+ else if ((flags & REQ_OP_MASK) == REQ_OP_READ)
type = HCTX_TYPE_READ;

return ctx->hctxs[type];
--
2.7.4
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