linux-kernel - Re: [PATCH v4 2/2] trace nvme submit queue status

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Message-ID: <20181218174750.GA14416@lst.de>
Date:   Tue, 18 Dec 2018 18:47:50 +0100
From:   "hch@....de" <hch@....de>
To:     Keith Busch <keith.busch@...el.com>
Cc:     yupeng <yupeng0921@...il.com>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>,
        "axboe@...com" <axboe@...com>, "hch@....de" <hch@....de>,
        "sagi@...mberg.me" <sagi@...mberg.me>,
        "jthumshirn@...e.de" <jthumshirn@...e.de>
Subject: Re: [PATCH v4 2/2] trace nvme submit queue status

On Tue, Dec 18, 2018 at 10:26:46AM -0700, Keith Busch wrote:
> No need for a space after the %s. __print_disk_name already appends a
> space if there's a disk name, and we don't want the extra space if there
> isn't one. Also, every other nvme trace has a ',' after each entry. Not
> a big deal, just minor format consistency.

Yeah.  What about something like this incremental patch to make the
trace formatting and argument passing match what we otherwise do:

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 2477bd906904..5a0bf6a24d50 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1004,8 +1004,7 @@ static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)
 	}
 
 	req = blk_mq_tag_to_rq(*nvmeq->tags, cqe->command_id);
-	trace_nvme_sq(req->rq_disk, nvmeq->qid, le16_to_cpu(cqe->sq_head),
-			nvmeq->sq_tail);
+	trace_nvme_sq(req, cqe->sq_head, nvmeq->sq_tail);
 	nvme_end_request(req, cqe->status, cqe->result);
 }
 
diff --git a/drivers/nvme/host/trace.h b/drivers/nvme/host/trace.h
index cf666709bc50..3564120aa7b3 100644
--- a/drivers/nvme/host/trace.h
+++ b/drivers/nvme/host/trace.h
@@ -185,22 +185,24 @@ TRACE_EVENT(nvme_async_event,
 #undef aer_name
 
 TRACE_EVENT(nvme_sq,
-	TP_PROTO(void *rq_disk, int qid, int sq_head, int sq_tail),
-	TP_ARGS(rq_disk, qid, sq_head, sq_tail),
+	TP_PROTO(struct request *req, __le16 sq_head, int sq_tail),
+	TP_ARGS(req, sq_head, sq_tail),
 	TP_STRUCT__entry(
+		__field(int, ctrl_id)
 		__array(char, disk, DISK_NAME_LEN)
 		__field(int, qid)
-		__field(int, sq_head)
-		__field(int, sq_tail)
+		__field(u16, sq_head)
+		__field(u16, sq_tail)
 	),
 	TP_fast_assign(
-		__assign_disk_name(__entry->disk, rq_disk);
-		__entry->qid = qid;
-		__entry->sq_head = sq_head;
+		__entry->ctrl_id = nvme_req(req)->ctrl->instance;
+		__assign_disk_name(__entry->disk, req->rq_disk);
+		__entry->qid = nvme_req_qid(req);
+		__entry->sq_head = le16_to_cpu(sq_head);
 		__entry->sq_tail = sq_tail;
 	),
-	TP_printk("nvme: %s qid=%d head=%d tail=%d",
-		__print_disk_name(__entry->disk),
+	TP_printk("nvme%d: %sqid=%d, head=%u, tail=%u",
+		__entry->ctrl_id, __print_disk_name(__entry->disk),
 		__entry->qid, __entry->sq_head, __entry->sq_tail
 	)
 );