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

From: Keith Busch <keith.busch@intel.com>
To: "hch@lst.de" <hch@lst.de>
Cc: yupeng <yupeng0921@gmail.com>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	"axboe@fb.com" <axboe@fb.com>,
	"sagi@grimberg.me" <sagi@grimberg.me>,
	"jthumshirn@suse.de" <jthumshirn@suse.de>
Subject: Re: [PATCH v4 2/2] trace nvme submit queue status
Date: Tue, 18 Dec 2018 11:03:07 -0700	[thread overview]
Message-ID: <20181218180306.GA19791@localhost.localdomain> (raw)
In-Reply-To: <20181218174750.GA14416@lst.de>

On Tue, Dec 18, 2018 at 06:47:50PM +0100, hch@lst.de wrote:
> 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:

Nice, that looks good. It's also necessary for admin commands since
there was no other way to see which controller a completion came from
without this.

Reviewed-by: Keith Busch <keith.busch@intel.com> 

> 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
>  	)
>  );