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* [PATCH] tracing: remove holes in events
@ 2021-03-11  9:44 Tony Lu
  2021-03-11 13:56 ` Steven Rostedt
  0 siblings, 1 reply; 3+ messages in thread
From: Tony Lu @ 2021-03-11  9:44 UTC (permalink / raw)
  To: rostedt, eric.dumazet, mingo; +Cc: linux-kernel, netdev

There are some holes in the event definitions, spaces are wasted. Based
on the analysis result of pahole and event format files, 22 events have
more than one hole. To change less and fix worst, 5 events are picked
up and fixed in this patch according the following rules.

Rules:

  - try not to affect reading habit and understanding of the fields;
  - can be completely fixed (all holes are removed);

NOTES:

  - changing the order of event fields breaks API compatibility,
    programs should parse and determine the real data order at runtime,
    instead of hard-coded the order of fields;
  - reduce holes as much as possible when adding / modifying;

Summary (#event_name #before -> #after):

 1. net_dev_start_xmit
    5 holes (10 bytes) -> 0

 2. net_dev_rx_verbose_template
    6 holes (17 bytes) -> 0

 3. tcp_probe
    3 holes (8 bytes) -> 0

 4. qdisc_dequeue
    2 holes (8 bytes) -> 0

 5. rpc_xdr_alignment
    2 holes (8 bytes) -> 0

Link: https://www.spinics.net/lists/netdev/msg726308.html
Link: https://www.spinics.net/lists/netdev/msg726451.html
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Tony Lu <tonylu@linux.alibaba.com>
---
 include/trace/events/net.h    | 42 +++++++++++++++++------------------
 include/trace/events/qdisc.h  |  4 ++--
 include/trace/events/sunrpc.h |  4 ++--
 include/trace/events/tcp.h    |  2 +-
 4 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/include/trace/events/net.h b/include/trace/events/net.h
index 2399073c3afc..b1db7ab88d4b 100644
--- a/include/trace/events/net.h
+++ b/include/trace/events/net.h
@@ -20,18 +20,18 @@ TRACE_EVENT(net_dev_start_xmit,
 	TP_STRUCT__entry(
 		__string(	name,			dev->name	)
 		__field(	u16,			queue_mapping	)
+		__field(	u16,			protocol	)
 		__field(	const void *,		skbaddr		)
+		__field(	u8,			ip_summed	)
 		__field(	bool,			vlan_tagged	)
 		__field(	u16,			vlan_proto	)
 		__field(	u16,			vlan_tci	)
-		__field(	u16,			protocol	)
-		__field(	u8,			ip_summed	)
+		__field(	bool,			transport_offset_valid)
+		__field(	u8,			tx_flags	)
 		__field(	unsigned int,		len		)
 		__field(	unsigned int,		data_len	)
 		__field(	int,			network_offset	)
-		__field(	bool,			transport_offset_valid)
 		__field(	int,			transport_offset)
-		__field(	u8,			tx_flags	)
 		__field(	u16,			gso_size	)
 		__field(	u16,			gso_segs	)
 		__field(	u16,			gso_type	)
@@ -40,19 +40,19 @@ TRACE_EVENT(net_dev_start_xmit,
 	TP_fast_assign(
 		__assign_str(name, dev->name);
 		__entry->queue_mapping = skb->queue_mapping;
+		__entry->protocol = ntohs(skb->protocol);
 		__entry->skbaddr = skb;
+		__entry->ip_summed = skb->ip_summed;
 		__entry->vlan_tagged = skb_vlan_tag_present(skb);
 		__entry->vlan_proto = ntohs(skb->vlan_proto);
 		__entry->vlan_tci = skb_vlan_tag_get(skb);
-		__entry->protocol = ntohs(skb->protocol);
-		__entry->ip_summed = skb->ip_summed;
+		__entry->transport_offset_valid =
+			skb_transport_header_was_set(skb);
+		__entry->tx_flags = skb_shinfo(skb)->tx_flags;
 		__entry->len = skb->len;
 		__entry->data_len = skb->data_len;
 		__entry->network_offset = skb_network_offset(skb);
-		__entry->transport_offset_valid =
-			skb_transport_header_was_set(skb);
 		__entry->transport_offset = skb_transport_offset(skb);
-		__entry->tx_flags = skb_shinfo(skb)->tx_flags;
 		__entry->gso_size = skb_shinfo(skb)->gso_size;
 		__entry->gso_segs = skb_shinfo(skb)->gso_segs;
 		__entry->gso_type = skb_shinfo(skb)->gso_type;
@@ -170,23 +170,23 @@ DECLARE_EVENT_CLASS(net_dev_rx_verbose_template,
 	TP_STRUCT__entry(
 		__string(	name,			skb->dev->name	)
 		__field(	unsigned int,		napi_id		)
-		__field(	u16,			queue_mapping	)
 		__field(	const void *,		skbaddr		)
+		__field(	u16,			queue_mapping	)
+		__field(	u8,			ip_summed	)
 		__field(	bool,			vlan_tagged	)
 		__field(	u16,			vlan_proto	)
 		__field(	u16,			vlan_tci	)
 		__field(	u16,			protocol	)
-		__field(	u8,			ip_summed	)
-		__field(	u32,			hash		)
 		__field(	bool,			l4_hash		)
+		__field(	bool,			mac_header_valid)
+		__field(	int,			mac_header	)
 		__field(	unsigned int,		len		)
 		__field(	unsigned int,		data_len	)
 		__field(	unsigned int,		truesize	)
-		__field(	bool,			mac_header_valid)
-		__field(	int,			mac_header	)
-		__field(	unsigned char,		nr_frags	)
+		__field(	u32,			hash		)
 		__field(	u16,			gso_size	)
 		__field(	u16,			gso_type	)
+		__field(	unsigned char,		nr_frags	)
 	),
 
 	TP_fast_assign(
@@ -196,23 +196,23 @@ DECLARE_EVENT_CLASS(net_dev_rx_verbose_template,
 #else
 		__entry->napi_id = 0;
 #endif
-		__entry->queue_mapping = skb->queue_mapping;
 		__entry->skbaddr = skb;
+		__entry->queue_mapping = skb->queue_mapping;
+		__entry->ip_summed = skb->ip_summed;
 		__entry->vlan_tagged = skb_vlan_tag_present(skb);
 		__entry->vlan_proto = ntohs(skb->vlan_proto);
 		__entry->vlan_tci = skb_vlan_tag_get(skb);
 		__entry->protocol = ntohs(skb->protocol);
-		__entry->ip_summed = skb->ip_summed;
-		__entry->hash = skb->hash;
 		__entry->l4_hash = skb->l4_hash;
+		__entry->mac_header_valid = skb_mac_header_was_set(skb);
+		__entry->mac_header = skb_mac_header(skb) - skb->data;
 		__entry->len = skb->len;
 		__entry->data_len = skb->data_len;
 		__entry->truesize = skb->truesize;
-		__entry->mac_header_valid = skb_mac_header_was_set(skb);
-		__entry->mac_header = skb_mac_header(skb) - skb->data;
-		__entry->nr_frags = skb_shinfo(skb)->nr_frags;
+		__entry->hash = skb->hash;
 		__entry->gso_size = skb_shinfo(skb)->gso_size;
 		__entry->gso_type = skb_shinfo(skb)->gso_type;
+		__entry->nr_frags = skb_shinfo(skb)->nr_frags;
 	),
 
 	TP_printk("dev=%s napi_id=%#x queue_mapping=%u skbaddr=%p vlan_tagged=%d vlan_proto=0x%04x vlan_tci=0x%04x protocol=0x%04x ip_summed=%d hash=0x%08x l4_hash=%d len=%u data_len=%u truesize=%u mac_header_valid=%d mac_header=%d nr_frags=%d gso_size=%d gso_type=%#x",
diff --git a/include/trace/events/qdisc.h b/include/trace/events/qdisc.h
index 330d32d84485..9e7d00256785 100644
--- a/include/trace/events/qdisc.h
+++ b/include/trace/events/qdisc.h
@@ -22,8 +22,8 @@ TRACE_EVENT(qdisc_dequeue,
 		__field(	struct Qdisc *,		qdisc	)
 		__field(const	struct netdev_queue *,	txq	)
 		__field(	int,			packets	)
-		__field(	void *,			skbaddr	)
 		__field(	int,			ifindex	)
+		__field(	void *,			skbaddr	)
 		__field(	u32,			handle	)
 		__field(	u32,			parent	)
 		__field(	unsigned long,		txq_state)
@@ -34,8 +34,8 @@ TRACE_EVENT(qdisc_dequeue,
 		__entry->qdisc		= qdisc;
 		__entry->txq		= txq;
 		__entry->packets	= skb ? packets : 0;
-		__entry->skbaddr	= skb;
 		__entry->ifindex	= txq->dev ? txq->dev->ifindex : 0;
+		__entry->skbaddr	= skb;
 		__entry->handle		= qdisc->handle;
 		__entry->parent		= qdisc->parent;
 		__entry->txq_state	= txq->state;
diff --git a/include/trace/events/sunrpc.h b/include/trace/events/sunrpc.h
index 036eb1f5c133..39f4fdcf4d0f 100644
--- a/include/trace/events/sunrpc.h
+++ b/include/trace/events/sunrpc.h
@@ -715,8 +715,8 @@ TRACE_EVENT(rpc_xdr_alignment,
 		__field(unsigned int, task_id)
 		__field(unsigned int, client_id)
 		__field(int, version)
-		__field(size_t, offset)
 		__field(unsigned int, copied)
+		__field(size_t, offset)
 		__field(const void *, head_base)
 		__field(size_t, head_len)
 		__field(const void *, tail_base)
@@ -739,8 +739,8 @@ TRACE_EVENT(rpc_xdr_alignment,
 		__entry->version = task->tk_client->cl_vers;
 		__assign_str(procedure, task->tk_msg.rpc_proc->p_name)
 
-		__entry->offset = offset;
 		__entry->copied = copied;
+		__entry->offset = offset;
 		__entry->head_base = xdr->buf->head[0].iov_base,
 		__entry->head_len = xdr->buf->head[0].iov_len,
 		__entry->page_len = xdr->buf->page_len,
diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index ba94857eea11..831abc267373 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -248,8 +248,8 @@ TRACE_EVENT(tcp_probe,
 		__field(__u16, sport)
 		__field(__u16, dport)
 		__field(__u16, family)
-		__field(__u32, mark)
 		__field(__u16, data_len)
+		__field(__u32, mark)
 		__field(__u32, snd_nxt)
 		__field(__u32, snd_una)
 		__field(__u32, snd_cwnd)
-- 
2.19.1.6.gb485710b


^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH] tracing: remove holes in events
  2021-03-11  9:44 [PATCH] tracing: remove holes in events Tony Lu
@ 2021-03-11 13:56 ` Steven Rostedt
  2021-03-12  2:21   ` Tony Lu
  0 siblings, 1 reply; 3+ messages in thread
From: Steven Rostedt @ 2021-03-11 13:56 UTC (permalink / raw)
  To: Tony Lu; +Cc: eric.dumazet, mingo, linux-kernel, netdev

On Thu, 11 Mar 2021 17:44:15 +0800
Tony Lu <tonylu@linux.alibaba.com> wrote:

> ---
>  include/trace/events/net.h    | 42 +++++++++++++++++------------------
>  include/trace/events/qdisc.h  |  4 ++--
>  include/trace/events/sunrpc.h |  4 ++--
>  include/trace/events/tcp.h    |  2 +-
>  4 files changed, 26 insertions(+), 26 deletions(-)


If all the above are owned by networking, then this patch needs to go
through the networking tree.

-- Steve

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [PATCH] tracing: remove holes in events
  2021-03-11 13:56 ` Steven Rostedt
@ 2021-03-12  2:21   ` Tony Lu
  0 siblings, 0 replies; 3+ messages in thread
From: Tony Lu @ 2021-03-12  2:21 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: eric.dumazet, mingo, linux-kernel, netdev

On Thu, Mar 11, 2021 at 08:56:19AM -0500, Steven Rostedt wrote:
> On Thu, 11 Mar 2021 17:44:15 +0800
> Tony Lu <tonylu@linux.alibaba.com> wrote:
> 
> > ---
> >  include/trace/events/net.h    | 42 +++++++++++++++++------------------
> >  include/trace/events/qdisc.h  |  4 ++--
> >  include/trace/events/sunrpc.h |  4 ++--
> >  include/trace/events/tcp.h    |  2 +-
> >  4 files changed, 26 insertions(+), 26 deletions(-)
> 
> 
> If all the above are owned by networking, then this patch needs to go
> through the networking tree.

Thanks, I will resend it.


Cheers,
Tony Lu

> 
> -- Steve

^ permalink raw reply	[flat|nested] 3+ messages in thread
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2021-03-11  9:44 [PATCH] tracing: remove holes in events Tony Lu
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2021-03-12  2:21   ` Tony Lu

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