@@ -247,6 +247,7 @@ static const char *const hctx_flag_name[] = {
HCTX_FLAG_NAME(NO_SCHED),
HCTX_FLAG_NAME(STACKING),
HCTX_FLAG_NAME(TAG_HCTX_SHARED),
+ HCTX_FLAG_NAME(MANAGED_IRQ),
};
#undef HCTX_FLAG_NAME
@@ -427,6 +427,15 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
}
EXPORT_SYMBOL(blk_mq_alloc_request);
+static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
+{
+ int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
+
+ if (cpu >= nr_cpu_ids)
+ cpu = cpumask_first(hctx->cpumask);
+ return cpu;
+}
+
struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
unsigned int op, blk_mq_req_flags_t flags, unsigned int hctx_idx)
{
@@ -468,7 +477,10 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
data.hctx = q->queue_hw_ctx[hctx_idx];
if (!blk_mq_hw_queue_mapped(data.hctx))
goto out_queue_exit;
- cpu = cpumask_first_and(data.hctx->cpumask, cpu_online_mask);
+
+ WARN_ON_ONCE(data.hctx->flags & BLK_MQ_F_MANAGED_IRQ);
+
+ cpu = blk_mq_first_mapped_cpu(data.hctx);
data.ctx = __blk_mq_get_ctx(q, cpu);
if (!q->elevator)
@@ -1501,15 +1513,6 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
hctx_unlock(hctx, srcu_idx);
}
-static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
-{
- int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
-
- if (cpu >= nr_cpu_ids)
- cpu = cpumask_first(hctx->cpumask);
- return cpu;
-}
-
/*
* It'd be great if the workqueue API had a way to pass
* in a mask and had some smarts for more clever placement.
@@ -403,6 +403,7 @@ enum {
*/
BLK_MQ_F_STACKING = 1 << 2,
BLK_MQ_F_TAG_HCTX_SHARED = 1 << 3,
+ BLK_MQ_F_MANAGED_IRQ = 1 << 4,
BLK_MQ_F_BLOCKING = 1 << 5,
BLK_MQ_F_NO_SCHED = 1 << 6,
BLK_MQ_F_ALLOC_POLICY_START_BIT = 8,
blk-mq deactivates one hctx when the last CPU in hctx->cpumask become offline by draining all requests originated from this hctx and moving new allocation on other active hctx. This way is for avoiding inflight IO in case of managed irq because managed irq is shutdown when the last CPU in the irq's affinity becomes offline. However, lots of drivers(nvme fc, rdma, tcp, loop, ...) don't use managed irq, so they needn't to deactivate hctx when the last CPU becomes offline. Also, some of them are the only user of blk_mq_alloc_request_hctx() which is used for connecting io queue. And their requirement is that the connect request needs to be submitted successfully via one specified hctx even though all CPUs in this hctx->cpumask have become offline. Preparing for addressing the requirement for nvme fc/rdma/loop by adding BLK_MQ_F_MANAGED_IRQ to not deactivate hctxs if managed irq isn't used. Finally, if one driver uses managed irq, it has to tell blk-mq via BLK_MQ_F_MANAGED_IRQ. Meantime blk-mq's cpu hotplug handling can be optimized a bit if managed irq isn't used. Given blk_mq_alloc_request_hctx() is always called by driver without BLK_MQ_F_MANAGED_IRQ, it is safe to take one offline cpu for getting the sw context. Signed-off-by: Ming Lei <ming.lei@redhat.com> --- block/blk-mq-debugfs.c | 1 + block/blk-mq.c | 23 +++++++++++++---------- include/linux/blk-mq.h | 1 + 3 files changed, 15 insertions(+), 10 deletions(-)