[PATCH bpf-next v3 3/5] nbd: add tracepoints for send/receive timing

Matt Mullins
2019-04-19T21:05:52Z

From: Andrew Hall <hall@fb.com>

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>
---
drivers/block/nbd.c | 8 ++++++
include/trace/events/nbd.h | 51 ++++++++++++++++++++++++++++++++++++++
2 files changed, 59 insertions(+)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 7393d04d255c..cb5ae6711ee0 100644
--- 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 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
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 5928255ed02e..9849956f34d8 100644
--- 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,
--
2.17.1