nbd: add tracepoints for send/receive timing

This adds four tracepoints to nbd, enabling separate tracing of payload
and header sending/receipt.

In the send path for headers that have already been sent, we also
explicitly initialize the handle so it can be referenced by the later
tracepoint.

Signed-off-by: Andrew Hall <hall@fb.com>
Signed-off-by: Matt Mullins <mmullins@fb.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 24cc10d..3e6c3d5 100644 (file)
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -513,6 +513,10 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
        if (sent) {
                if (sent >= sizeof(request)) {
                        skip = sent - sizeof(request);
+
+                       /* initialize handle for tracing purposes */
+                       handle = nbd_cmd_handle(cmd);
+
                        goto send_pages;
                }
                iov_iter_advance(&from, sent);
@@ -536,6 +540,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
                (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
        result = sock_xmit(nbd, index, 1, &from,
                        (type == NBD_CMD_WRITE) ? MSG_MORE : 0, &sent);
+       trace_nbd_header_sent(req, handle);
        if (result <= 0) {
                if (was_interrupted(result)) {
                        /* If we havne't sent anything we can just return BUSY,
@@ -608,6 +613,7 @@ send_pages:
                bio = next;
        }
 out:
+       trace_nbd_payload_sent(req, handle);
        nsock->pending = NULL;
        nsock->sent = 0;
        return 0;
@@ -655,6 +661,7 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
                        tag, req);
                return ERR_PTR(-ENOENT);
        }
+       trace_nbd_header_received(req, handle);
        cmd = blk_mq_rq_to_pdu(req);
 
        mutex_lock(&cmd->lock);
@@ -708,6 +715,7 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
                }
        }
 out:
+       trace_nbd_payload_received(req, handle);
        mutex_unlock(&cmd->lock);
        return ret ? ERR_PTR(ret) : cmd;
 }

diff --git a/include/trace/events/nbd.h b/include/trace/events/nbd.h
index 5928255..9849956 100644 (file)
--- a/include/trace/events/nbd.h
+++ b/include/trace/events/nbd.h
@@ -7,6 +7,57 @@
 
 #include <linux/tracepoint.h>
 
+DECLARE_EVENT_CLASS(nbd_transport_event,
+
+       TP_PROTO(struct request *req, u64 handle),
+
+       TP_ARGS(req, handle),
+
+       TP_STRUCT__entry(
+               __field(struct request *, req)
+               __field(u64, handle)
+       ),
+
+       TP_fast_assign(
+               __entry->req = req;
+               __entry->handle = handle;
+       ),
+
+       TP_printk(
+               "nbd transport event: request %p, handle 0x%016llx",
+               __entry->req,
+               __entry->handle
+       )
+);
+
+DEFINE_EVENT(nbd_transport_event, nbd_header_sent,
+
+       TP_PROTO(struct request *req, u64 handle),
+
+       TP_ARGS(req, handle)
+);
+
+DEFINE_EVENT(nbd_transport_event, nbd_payload_sent,
+
+       TP_PROTO(struct request *req, u64 handle),
+
+       TP_ARGS(req, handle)
+);
+
+DEFINE_EVENT(nbd_transport_event, nbd_header_received,
+
+       TP_PROTO(struct request *req, u64 handle),
+
+       TP_ARGS(req, handle)
+);
+
+DEFINE_EVENT(nbd_transport_event, nbd_payload_received,
+
+       TP_PROTO(struct request *req, u64 handle),
+
+       TP_ARGS(req, handle)
+);
+
 DECLARE_EVENT_CLASS(nbd_send_request,
 
        TP_PROTO(struct nbd_request *nbd_request, int index,