[PATCH 1/2] blk-mq: handle single queue case in blk_mq_hctx_next_cpu

From: Christoph Hellwig
Date: Mon Nov 03 2014 - 03:23:35 EST


Don't duplicate the code to handle the not cpu bounce case in the
caller, do it inside blk_mq_hctx_next_cpu instead.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
block/blk-mq.c | 34 +++++++++++++---------------------
1 file changed, 13 insertions(+), 21 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index b355b59..22e50a5 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -780,10 +780,11 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
*/
static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
{
- int cpu = hctx->next_cpu;
+ if (hctx->queue->nr_hw_queues == 1)
+ return WORK_CPU_UNBOUND;

if (--hctx->next_cpu_batch <= 0) {
- int next_cpu;
+ int cpu = hctx->next_cpu, next_cpu;

next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
if (next_cpu >= nr_cpu_ids)
@@ -791,9 +792,11 @@ static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)

hctx->next_cpu = next_cpu;
hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
+
+ return cpu;
}

- return cpu;
+ return hctx->next_cpu;
}

void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
@@ -801,16 +804,13 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
return;

- if (!async && cpumask_test_cpu(smp_processor_id(), hctx->cpumask))
+ if (!async && cpumask_test_cpu(smp_processor_id(), hctx->cpumask)) {
__blk_mq_run_hw_queue(hctx);
- else if (hctx->queue->nr_hw_queues == 1)
- kblockd_schedule_delayed_work(&hctx->run_work, 0);
- else {
- unsigned int cpu;
-
- cpu = blk_mq_hctx_next_cpu(hctx);
- kblockd_schedule_delayed_work_on(cpu, &hctx->run_work, 0);
+ return;
}
+
+ kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
+ &hctx->run_work, 0);
}

void blk_mq_run_queues(struct request_queue *q, bool async)
@@ -908,16 +908,8 @@ static void blk_mq_delay_work_fn(struct work_struct *work)

void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
{
- unsigned long tmo = msecs_to_jiffies(msecs);
-
- if (hctx->queue->nr_hw_queues == 1)
- kblockd_schedule_delayed_work(&hctx->delay_work, tmo);
- else {
- unsigned int cpu;
-
- cpu = blk_mq_hctx_next_cpu(hctx);
- kblockd_schedule_delayed_work_on(cpu, &hctx->delay_work, tmo);
- }
+ kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
+ &hctx->delay_work, msecs_to_jiffies(msecs));
}
EXPORT_SYMBOL(blk_mq_delay_queue);

--
1.9.1

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