Both the softirq path for single queue devices and the multi-queue
completion handler share the same logic to figure out if we need an
IPI for the completion and eventually issue it. Merge the two
versions into a single unified code path.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
block/blk-mq.c | 85 ++++++++++++--------------------------------------
1 file changed, 20 insertions(+), 65 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 059d30c522f2ad..11c706a9942043 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -600,8 +600,11 @@ static __latent_entropy void blk_done_softirq(struct softirq_action *h)
static void blk_mq_trigger_softirq(struct request *rq)
{
- struct list_head *list = this_cpu_ptr(&blk_cpu_done);
+ struct list_head *list;
+ unsigned long flags;
+ local_irq_save(flags);
+ list = this_cpu_ptr(&blk_cpu_done);
list_add_tail(&rq->ipi_list, list);
/*
@@ -611,11 +614,7 @@ static void blk_mq_trigger_softirq(struct request *rq)
*/
if (list->next == &rq->ipi_list)
raise_softirq_irqoff(BLOCK_SOFTIRQ);
-}
-
-static void trigger_softirq(void *data)
-{
- blk_mq_trigger_softirq(data);
+ local_irq_restore(flags);
}
static int blk_softirq_cpu_dead(unsigned int cpu)
@@ -633,56 +632,26 @@ static int blk_softirq_cpu_dead(unsigned int cpu)
return 0;
}
-static void __blk_complete_request(struct request *req)
+static void __blk_mq_complete_request(struct request *rq)
{
- struct request_queue *q = req->q;
- int cpu, ccpu = req->mq_ctx->cpu;
- unsigned long flags;
- bool shared = false;
-
- BUG_ON(!q->mq_ops->complete);
-
- local_irq_save(flags);
- cpu = smp_processor_id();
-
- /*
- * Select completion CPU
- */
- if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) && ccpu != -1) {
- if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
- shared = cpus_share_cache(cpu, ccpu);
- } else
- ccpu = cpu;
-
/*
- * If current CPU and requested CPU share a cache, run the softirq on
- * the current CPU. One might concern this is just like
- * QUEUE_FLAG_SAME_FORCE, but actually not. blk_complete_request() is
- * running in interrupt handler, and currently I/O controller doesn't
- * support multiple interrupts, so current CPU is unique actually. This
- * avoids IPI sending from current CPU to the first CPU of a group.
+ * For most of single queue controllers, there is only one irq vector
+ * for handling I/O completion, and the only irq's affinity is set
+ * to all possible CPUs. On most of ARCHs, this affinity means the irq
+ * is handled on one specific CPU.
+ *
+ * So complete I/O requests in softirq context in case of single queue
+ * devices to avoid degrading I/O performance due to irqsoff latency.
*/
- if (IS_ENABLED(CONFIG_SMP) &&
- ccpu != cpu && !shared && cpu_online(ccpu)) {
- call_single_data_t *data = &req->csd;
-
- data->func = trigger_softirq;
- data->info = req;
- data->flags = 0;
- smp_call_function_single_async(cpu, data);
- } else {
- blk_mq_trigger_softirq(req);
- }
-
- local_irq_restore(flags);
+ if (rq->q->nr_hw_queues == 1)
+ blk_mq_trigger_softirq(rq);
+ else
+ rq->q->mq_ops->complete(rq);
}
static void __blk_mq_complete_request_remote(void *data)
{
- struct request *rq = data;
- struct request_queue *q = rq->q;
-
- q->mq_ops->complete(rq);
+ __blk_mq_complete_request(data);
}
/**
@@ -713,23 +682,9 @@ void blk_mq_force_complete_rq(struct request *rq)
return;
}
- /*
- * Most of single queue controllers, there is only one irq vector
- * for handling IO completion, and the only irq's affinity is set
- * as all possible CPUs. On most of ARCHs, this affinity means the
- * irq is handled on one specific CPU.
- *
- * So complete IO reqeust in softirq context in case of single queue
- * for not degrading IO performance by irqsoff latency.
- */
- if (q->nr_hw_queues == 1) {
- __blk_complete_request(rq);
- return;
- }
-
if (!IS_ENABLED(CONFIG_SMP) ||
!test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) {
- q->mq_ops->complete(rq);
+ __blk_mq_complete_request(rq);
return;
}
@@ -743,7 +698,7 @@ void blk_mq_force_complete_rq(struct request *rq)
rq->csd.flags = 0;
smp_call_function_single_async(ctx->cpu, &rq->csd);
} else {
- q->mq_ops->complete(rq);
+ __blk_mq_complete_request(rq);
}
put_cpu();
}
--
2.26.2
