Re: [very-RFC 6/8] Add TSN event-tracing

On Sun, Jun 12, 2016 at 12:58:03PM -0400, Steven Rostedt wrote:

On Sun, 12 Jun 2016 01:01:34 +0200
Henrik Austad [off-list ref] wrote:

quoted

From: Henrik Austad <redacted>

This needs refactoring and should be updated to use TRACE_CLASS, but for
now it provides a fair debug-window into TSN.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Steven Rostedt <rostedt@goodmis.org> (maintainer:TRACING)
Cc: Ingo Molnar <mingo@redhat.com> (maintainer:TRACING)
Signed-off-by: Henrik Austad <redacted>
---
 include/trace/events/tsn.h | 349 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 349 insertions(+)
 create mode 100644 include/trace/events/tsn.h

diff --git a/include/trace/events/tsn.h b/include/trace/events/tsn.h
new file mode 100644
index 0000000..ac1f31b
--- /dev/null
+++ b/include/trace/events/tsn.h

@@ -0,0 +1,349 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM tsn
+
+#if !defined(_TRACE_TSN_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_TSN_H
+
+#include <linux/tsn.h>
+#include <linux/tracepoint.h>
+
+#include <linux/if_ether.h>
+#include <linux/if_vlan.h>
+/* #include <linux/skbuff.h> */
+
+/* FIXME: update to TRACE_CLASS to reduce overhead */

I'm curious to why I didn't do this now. A class would make less
duplication of typing too ;-)

Yeah, I found this in a really great article written by some tracing-dude, 
I hear he talks really, really fast!

https://lwn.net/Articles/381064/

quoted

+TRACE_EVENT(tsn_buffer_write,
+
+	TP_PROTO(struct tsn_link *link,
+		size_t bytes),
+
+	TP_ARGS(link, bytes),
+
+	TP_STRUCT__entry(
+		__field(u64, stream_id)
+		__field(size_t, size)
+		__field(size_t, bsize)
+		__field(size_t, size_left)
+		__field(void *, buffer)
+		__field(void *, head)
+		__field(void *, tail)
+		__field(void *, end)
+		),
+
+	TP_fast_assign(
+		__entry->stream_id = link->stream_id;
+		__entry->size = bytes;
+		__entry->bsize = link->used_buffer_size;
+		__entry->size_left = (link->head - link->tail) % link->used_buffer_size;

Move this logic into the print statement, since you save head and tail.

Ok, any particular reason?

quoted

+		__entry->buffer = link->buffer;
+		__entry->head = link->head;
+		__entry->tail = link->tail;
+		__entry->end = link->end;
+		),
+
+	TP_printk("stream_id=%llu, copy=%zd, buffer: %zd, avail=%zd, [buffer=%p, head=%p, tail=%p, end=%p]",
+		__entry->stream_id, __entry->size, __entry->bsize, __entry->size_left,

 __entry->stream_id, __entry->size, __entry->bsize,
 (__entry->head - __entry->tail) % __entry->bsize,

Ok, so is this about saving space by dropping one intermediate value, or is 
it some other point I'm missing here?

quoted

+		__entry->buffer,    __entry->head, __entry->tail,  __entry->end)
+
+	);
+
+TRACE_EVENT(tsn_buffer_write_net,
+
+	TP_PROTO(struct tsn_link *link,
+		size_t bytes),
+
+	TP_ARGS(link, bytes),
+
+	TP_STRUCT__entry(
+		__field(u64, stream_id)
+		__field(size_t, size)
+		__field(size_t, bsize)
+		__field(size_t, size_left)
+		__field(void *, buffer)
+		__field(void *, head)
+		__field(void *, tail)
+		__field(void *, end)
+		),
+
+	TP_fast_assign(
+		__entry->stream_id = link->stream_id;
+		__entry->size = bytes;
+		__entry->bsize = link->used_buffer_size;
+		__entry->size_left = (link->head - link->tail) % link->used_buffer_size;
+		__entry->buffer = link->buffer;
+		__entry->head = link->head;
+		__entry->tail = link->tail;
+		__entry->end = link->end;
+		),
+
+	TP_printk("stream_id=%llu, copy=%zd, buffer: %zd, avail=%zd, [buffer=%p, head=%p, tail=%p, end=%p]",
+		__entry->stream_id, __entry->size, __entry->bsize, __entry->size_left,
+		__entry->buffer,    __entry->head, __entry->tail,  __entry->end)
+
+	);
+
+
+TRACE_EVENT(tsn_buffer_read,
+
+	TP_PROTO(struct tsn_link *link,
+		size_t bytes),
+
+	TP_ARGS(link, bytes),
+
+	TP_STRUCT__entry(
+		__field(u64, stream_id)
+		__field(size_t, size)
+		__field(size_t, bsize)
+		__field(size_t, size_left)
+		__field(void *, buffer)
+		__field(void *, head)
+		__field(void *, tail)
+		__field(void *, end)
+		),
+
+	TP_fast_assign(
+		__entry->stream_id = link->stream_id;
+		__entry->size = bytes;
+		__entry->bsize = link->used_buffer_size;
+		__entry->size_left = (link->head - link->tail) % link->used_buffer_size;
+		__entry->buffer = link->buffer;
+		__entry->head = link->head;
+		__entry->tail = link->tail;
+		__entry->end = link->end;
+		),
+
+	TP_printk("stream_id=%llu, copy=%zd, buffer: %zd, avail=%zd, [buffer=%p, head=%p, tail=%p, end=%p]",
+		__entry->stream_id, __entry->size, __entry->bsize, __entry->size_left,
+		__entry->buffer,    __entry->head, __entry->tail,  __entry->end)
+
+	);
+
+TRACE_EVENT(tsn_refill,
+
+	TP_PROTO(struct tsn_link *link,
+		size_t reported_avail),
+
+	TP_ARGS(link, reported_avail),
+
+	TP_STRUCT__entry(
+		__field(u64, stream_id)
+		__field(size_t, bsize)
+		__field(size_t, size_left)
+		__field(size_t, reported_left)
+		__field(size_t, low_water)
+		),
+
+	TP_fast_assign(
+		__entry->stream_id = link->stream_id;
+		__entry->bsize = link->used_buffer_size;
+		__entry->size_left = (link->head - link->tail) % link->used_buffer_size;

As you don't save head and tail here, this logic needs to remain.

quoted

+		__entry->reported_left = reported_avail;
+		__entry->low_water = link->low_water_mark;
+		),
+
+	TP_printk("stream_id=%llu, buffer=%zd, avail=%zd, reported=%zd, low=%zd",
+		__entry->stream_id, __entry->bsize, __entry->size_left, __entry->reported_left, __entry->low_water)
+	);
+
+TRACE_EVENT(tsn_send_batch,
+
+	TP_PROTO(struct tsn_link *link,
+		int num_send,
+		u64 ts_base_ns,
+		u64 ts_delta_ns),
+
+	TP_ARGS(link, num_send, ts_base_ns, ts_delta_ns),
+
+	TP_STRUCT__entry(
+		__field(u64, stream_id)
+		__field(int, seqnr)
+		__field(int, num_send)
+		__field(u64, ts_base_ns)
+		__field(u64, ts_delta_ns)
+		),
+
+	TP_fast_assign(
+		__entry->stream_id   = link->stream_id;
+		__entry->seqnr	     = (int)link->last_seqnr;
+		__entry->ts_base_ns  = ts_base_ns;
+		__entry->ts_delta_ns = ts_delta_ns;
+		__entry->num_send    = num_send;
+		),
+
+	TP_printk("stream_id=%llu, seqnr=%d, num_send=%d, ts_base_ns=%llu, ts_delta_ns=%llu",
+		__entry->stream_id, __entry->seqnr, __entry->num_send, __entry->ts_base_ns, __entry->ts_delta_ns)
+	);
+
+
+TRACE_EVENT(tsn_rx_handler,
+
+	TP_PROTO(struct tsn_link *link,
+		const struct ethhdr *ethhdr,
+		u64 sid),
+
+	TP_ARGS(link, ethhdr, sid),
+
+	TP_STRUCT__entry(
+		__field(char *, name)
+		__field(u16, proto)
+		__field(u64, sid)
+		__field(u64, link_sid)
+		),
+	TP_fast_assign(
+		__entry->name  = link->nic->name;
+		__entry->proto = ethhdr->h_proto;
+		__entry->sid   = sid;
+		__entry->link_sid = link->stream_id;
+		),
+
+	TP_printk("name=%s, proto: 0x%04x, stream_id=%llu, link->sid=%llu",
+		__entry->name, ntohs(__entry->proto), __entry->sid, __entry->link_sid)
+	);
+
+TRACE_EVENT(tsn_du,
+
+	TP_PROTO(struct tsn_link *link,
+		size_t bytes),
+
+	TP_ARGS(link, bytes),
+
+	TP_STRUCT__entry(
+		__field(u64, link_sid)
+		__field(size_t, bytes)
+		),
+	TP_fast_assign(
+		__entry->link_sid = link->stream_id;
+		__entry->bytes = bytes;
+		),
+
+	TP_printk("stream_id=%llu,bytes=%zu",
+		__entry->link_sid, __entry->bytes)
+);
+
+TRACE_EVENT(tsn_set_buffer,
+
+	TP_PROTO(struct tsn_link *link, size_t bufsize),
+
+	TP_ARGS(link, bufsize),
+
+	TP_STRUCT__entry(
+		__field(u64,  stream_id)
+		__field(size_t, size)
+		),
+
+	TP_fast_assign(
+		__entry->stream_id = link->stream_id;
+		__entry->size = bufsize;
+		),
+
+	TP_printk("stream_id=%llu,buffer_size=%zu",
+		__entry->stream_id, __entry->size)
+
+	);
+
+TRACE_EVENT(tsn_free_buffer,
+
+	TP_PROTO(struct tsn_link *link),
+
+	TP_ARGS(link),
+
+	TP_STRUCT__entry(
+		__field(u64,  stream_id)
+		__field(size_t,	 bufsize)
+		),
+
+	TP_fast_assign(
+		__entry->stream_id = link->stream_id;
+		__entry->bufsize = link->buffer_size;
+		),
+
+	TP_printk("stream_id=%llu,size:%zd",
+		__entry->stream_id, __entry->bufsize)
+
+	);
+
+TRACE_EVENT(tsn_buffer_drain,
+
+	TP_PROTO(struct tsn_link *link, size_t used),
+
+	TP_ARGS(link, used),
+
+	TP_STRUCT__entry(
+		__field(u64, stream_id)
+		__field(size_t, used)
+	),
+
+	TP_fast_assign(
+		__entry->stream_id = link->stream_id;
+		__entry->used = used;
+	),
+
+	TP_printk("stream_id=%llu,used=%zu",
+		__entry->stream_id, __entry->used)
+
+);
+/* TODO: too long, need cleanup.
+ */
+TRACE_EVENT(tsn_pre_tx,
+
+	TP_PROTO(struct tsn_link *link, struct sk_buff *skb, size_t bytes),
+
+	TP_ARGS(link, skb, bytes),
+
+	TP_STRUCT__entry(
+		__field(u64, stream_id)
+		__field(u32, vlan_tag)
+		__field(size_t, bytes)
+		__field(size_t, data_len)
+		__field(unsigned int, headlen)
+		__field(u16, protocol)
+		__field(u16, prot_native)
+		__field(int, tx_idx)
+		__field(u16, mac_len)
+		__field(u16, hdr_len)
+		__field(u16, vlan_tci)
+		__field(u16, mac_header)
+		__field(unsigned int, tail)
+		__field(unsigned int, end)
+		__field(unsigned int, truesize)
+		),
+
+	TP_fast_assign(
+		__entry->stream_id = link->stream_id;
+		__entry->vlan_tag = (skb_vlan_tag_present(skb) ? skb_vlan_tag_get(skb) : 0);
+		__entry->bytes = bytes;
+		__entry->data_len = skb->data_len;
+		__entry->headlen = skb_headlen(skb);
+		__entry->protocol = ntohs(vlan_get_protocol(skb));

Maybe it would be better to do the ntohs() in the TP_printk() as well.

quoted

+		__entry->prot_native = ntohs(skb->protocol);

here too.

quoted

+		__entry->tx_idx = skb_get_queue_mapping(skb);
+
+		__entry->mac_len = skb->mac_len;
+		__entry->hdr_len = skb->hdr_len;
+		__entry->vlan_tci = skb->vlan_tci;
+		__entry->mac_header = skb->mac_header;
+		__entry->tail = (unsigned int)skb->tail;
+		__entry->end  = (unsigned int)skb->end;
+		__entry->truesize = skb->truesize;
+		),
+
+	TP_printk("stream_id=%llu,vlan_tag=0x%04x,data_size=%zd,data_len=%zd,headlen=%u,proto=0x%04x (0x%04x),tx_idx=%d,mac_len=%u,hdr_len=%u,vlan_tci=0x%02x,mac_header=0x%02x,tail=%u,end=%u,truesize=%u",
+		__entry->stream_id,
+		__entry->vlan_tag,
+		__entry->bytes,
+		__entry->data_len,
+		__entry->headlen,
+		__entry->protocol,
+		__entry->prot_native, __entry->tx_idx,
+		__entry->mac_len,
+		__entry->hdr_len,
+		__entry->vlan_tci,
+		__entry->mac_header,

Is this an ether mac header? If so we support %M. But as it's defined
as only u16, it doesn't seem like it can be.

Actually, looking at the output, I'm not quite sure what it is that I 
wanted to grab with that, the skb->mac_header should give an offset into 
the header-area of skb, so it should be a constant offset from skb->head 
(that is an actual pointer).

I *think* I wanted to make sure I updated things correctly so that the 
offset didn't suddenly change, but the fact that I'm no longer sure 
indicates that I should just drop that one. That whole printout is too long 
anyway..

Thanks for pointing a finger at this!


I'm still a bit stymied as to why logic should be in TP_printk() and not 
TP_fast_assign(). Not that I really have any preferences either way, just 
curious.



-- 
Henrik Austad