On 10/13/21 10:33 AM, Jens Axboe wrote:
> On 10/13/21 10:13 AM, Christoph Hellwig wrote:
>> On Wed, Oct 13, 2021 at 10:04:36AM -0600, Jens Axboe wrote:
>>> On 10/13/21 9:50 AM, Christoph Hellwig wrote:
>>>> On Wed, Oct 13, 2021 at 09:42:23AM -0600, Jens Axboe wrote:
>>>>> Something like this?
>>>>
>>>> Something like that. Although without making the new function inline
>>>> this will generate an indirect call.
>>>
>>> It will, but I don't see how we can have it both ways...
>>
>> Last time I played with these optimization gcc did inline function
>> pointers passed to __always_inline function into the calling
>> function. That is you can keep the source level abstraction but get the
>> code generation as if it was open coded.
>
> Gotcha, so place nvme_complete_batch() in the nvme.h header. That might
> work, let me give it a whirl.
Looks like this, and it is indeed not an indirect call. I'll re-test the
series and send out a v2.
commit 70ed26ee000d626105b0d807545af42e6d95a323
Author: Jens Axboe <axboe@xxxxxxxxx>
Date: Fri Oct 8 05:59:37 2021 -0600
nvme: add support for batched completion of polled IO
Take advantage of struct io_batch, if passed in to the nvme poll handler.
If it's set, rather than complete each request individually inline, store
them in the io_batch list. We only do so for requests that will complete
successfully, anything else will be completed inline as before.
Add an mq_ops->complete_batch() handler to do the post-processing of
the io_batch list once polling is complete.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index c2c2e8545292..4b14258a3bac 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -346,15 +346,19 @@ static inline enum nvme_disposition nvme_decide_disposition(struct request *req)
return RETRY;
}
-static inline void nvme_end_req(struct request *req)
+static inline void nvme_end_req_zoned(struct request *req)
{
- blk_status_t status = nvme_error_status(nvme_req(req)->status);
-
if (IS_ENABLED(CONFIG_BLK_DEV_ZONED) &&
req_op(req) == REQ_OP_ZONE_APPEND)
req->__sector = nvme_lba_to_sect(req->q->queuedata,
le64_to_cpu(nvme_req(req)->result.u64));
+}
+
+static inline void nvme_end_req(struct request *req)
+{
+ blk_status_t status = nvme_error_status(nvme_req(req)->status);
+ nvme_end_req_zoned(req);
nvme_trace_bio_complete(req);
blk_mq_end_request(req, status);
}
@@ -381,6 +385,14 @@ void nvme_complete_rq(struct request *req)
}
EXPORT_SYMBOL_GPL(nvme_complete_rq);
+void nvme_complete_batch_req(struct request *req)
+{
+ nvme_cleanup_cmd(req);
+ nvme_end_req_zoned(req);
+ req->status = BLK_STS_OK;
+}
+EXPORT_SYMBOL_GPL(nvme_complete_batch_req);
+
/*
* Called to unwind from ->queue_rq on a failed command submission so that the
* multipathing code gets called to potentially failover to another path.
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index ed79a6c7e804..e0c079f704cf 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -638,6 +638,23 @@ static inline bool nvme_is_aen_req(u16 qid, __u16 command_id)
}
void nvme_complete_rq(struct request *req);
+void nvme_complete_batch_req(struct request *req);
+
+static __always_inline void nvme_complete_batch(struct io_batch *iob,
+ void (*fn)(struct request *rq))
+{
+ struct request *req;
+
+ req = rq_list_peek(&iob->req_list);
+ while (req) {
+ fn(req);
+ nvme_complete_batch_req(req);
+ req = rq_list_next(req);
+ }
+
+ blk_mq_end_request_batch(iob);
+}
+
blk_status_t nvme_host_path_error(struct request *req);
bool nvme_cancel_request(struct request *req, void *data, bool reserved);
void nvme_cancel_tagset(struct nvme_ctrl *ctrl);
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 9db6e23f41ef..ae253f6f5c80 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -959,7 +959,7 @@ static blk_status_t nvme_queue_rq(struct blk_mq_hw_ctx *hctx,
return ret;
}
-static void nvme_pci_complete_rq(struct request *req)
+static __always_inline void nvme_pci_unmap_rq(struct request *req)
{
struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
struct nvme_dev *dev = iod->nvmeq->dev;
@@ -969,9 +969,19 @@ static void nvme_pci_complete_rq(struct request *req)
rq_integrity_vec(req)->bv_len, rq_data_dir(req));
if (blk_rq_nr_phys_segments(req))
nvme_unmap_data(dev, req);
+}
+
+static void nvme_pci_complete_rq(struct request *req)
+{
+ nvme_pci_unmap_rq(req);
nvme_complete_rq(req);
}
+static void nvme_pci_complete_batch(struct io_batch *iob)
+{
+ nvme_complete_batch(iob, nvme_pci_unmap_rq);
+}
+
/* We read the CQE phase first to check if the rest of the entry is valid */
static inline bool nvme_cqe_pending(struct nvme_queue *nvmeq)
{
@@ -996,7 +1006,8 @@ static inline struct blk_mq_tags *nvme_queue_tagset(struct nvme_queue *nvmeq)
return nvmeq->dev->tagset.tags[nvmeq->qid - 1];
}
-static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)
+static inline void nvme_handle_cqe(struct nvme_queue *nvmeq,
+ struct io_batch *iob, u16 idx)
{
struct nvme_completion *cqe = &nvmeq->cqes[idx];
__u16 command_id = READ_ONCE(cqe->command_id);
@@ -1023,8 +1034,17 @@ static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)
}
trace_nvme_sq(req, cqe->sq_head, nvmeq->sq_tail);
- if (!nvme_try_complete_req(req, cqe->status, cqe->result))
- nvme_pci_complete_rq(req);
+ if (!nvme_try_complete_req(req, cqe->status, cqe->result)) {
+ /*
+ * Do normal inline completion if we don't have a batch
+ * list, if we have an end_io handler, or if the status of
+ * the request isn't just normal success.
+ */
+ if (!iob || req->end_io || nvme_req(req)->status)
+ nvme_pci_complete_rq(req);
+ else
+ rq_list_add_tail(&iob->req_list, req);
+ }
}
static inline void nvme_update_cq_head(struct nvme_queue *nvmeq)
@@ -1050,7 +1070,7 @@ static inline int nvme_process_cq(struct nvme_queue *nvmeq)
* the cqe requires a full read memory barrier
*/
dma_rmb();
- nvme_handle_cqe(nvmeq, nvmeq->cq_head);
+ nvme_handle_cqe(nvmeq, NULL, nvmeq->cq_head);
nvme_update_cq_head(nvmeq);
}
@@ -1092,6 +1112,27 @@ static void nvme_poll_irqdisable(struct nvme_queue *nvmeq)
enable_irq(pci_irq_vector(pdev, nvmeq->cq_vector));
}
+static inline int nvme_poll_cq(struct nvme_queue *nvmeq, struct io_batch *iob)
+{
+ int found = 0;
+
+ while (nvme_cqe_pending(nvmeq)) {
+ found++;
+ /*
+ * load-load control dependency between phase and the rest of
+ * the cqe requires a full read memory barrier
+ */
+ dma_rmb();
+ nvme_handle_cqe(nvmeq, iob, nvmeq->cq_head);
+ nvme_update_cq_head(nvmeq);
+ }
+
+ if (found)
+ nvme_ring_cq_doorbell(nvmeq);
+ return found;
+}
+
+
static int nvme_poll(struct blk_mq_hw_ctx *hctx, struct io_batch *iob)
{
struct nvme_queue *nvmeq = hctx->driver_data;
@@ -1101,7 +1142,7 @@ static int nvme_poll(struct blk_mq_hw_ctx *hctx, struct io_batch *iob)
return 0;
spin_lock(&nvmeq->cq_poll_lock);
- found = nvme_process_cq(nvmeq);
+ found = nvme_poll_cq(nvmeq, iob);
spin_unlock(&nvmeq->cq_poll_lock);
return found;
@@ -1639,6 +1680,7 @@ static const struct blk_mq_ops nvme_mq_admin_ops = {
static const struct blk_mq_ops nvme_mq_ops = {
.queue_rq = nvme_queue_rq,
.complete = nvme_pci_complete_rq,
+ .complete_batch = nvme_pci_complete_batch,
.commit_rqs = nvme_commit_rqs,
.init_hctx = nvme_init_hctx,
.init_request = nvme_init_request,
--
Jens Axboe
