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authorGeneviève Bastien <gbastien@versatic.net>2018-11-27 12:52:39 -0500
committerDavid S. Miller <davem@davemloft.net>2018-11-30 13:23:25 -0800
commitb0e3f1bdf9e7140fd1151af575f468b5827a61e1 (patch)
tree7aba1b163e88451acfc69e0a168bb4d84cf4cea0
parentnet/flow_dissector: correct comments on enum flow_dissector_key_id (diff)
downloadlinux-dev-b0e3f1bdf9e7140fd1151af575f468b5827a61e1.tar.xz
linux-dev-b0e3f1bdf9e7140fd1151af575f468b5827a61e1.zip
net: Add trace events for all receive exit points
Trace events are already present for the receive entry points, to indicate how the reception entered the stack. This patch adds the corresponding exit trace events that will bound the reception such that all events occurring between the entry and the exit can be considered as part of the reception context. This greatly helps for dependency and root cause analyses. Without this, it is not possible with tracepoint instrumentation to determine whether a sched_wakeup event following a netif_receive_skb event is the result of the packet reception or a simple coincidence after further processing by the thread. It is possible using other mechanisms like kretprobes, but considering the "entry" points are already present, it would be good to add the matching exit events. In addition to linking packets with wakeups, the entry/exit event pair can also be used to perform network stack latency analyses. Signed-off-by: Geneviève Bastien <gbastien@versatic.net> CC: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> CC: Steven Rostedt <rostedt@goodmis.org> CC: Ingo Molnar <mingo@redhat.com> CC: David S. Miller <davem@davemloft.net> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> (tracing side) Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/trace/events/net.h59
-rw-r--r--net/core/dev.c35
2 files changed, 88 insertions, 6 deletions
diff --git a/include/trace/events/net.h b/include/trace/events/net.h
index 00aa72ce0e7c..1efd7d9b25fe 100644
--- a/include/trace/events/net.h
+++ b/include/trace/events/net.h
@@ -244,6 +244,65 @@ DEFINE_EVENT(net_dev_rx_verbose_template, netif_rx_ni_entry,
TP_ARGS(skb)
);
+DECLARE_EVENT_CLASS(net_dev_rx_exit_template,
+
+ TP_PROTO(int ret),
+
+ TP_ARGS(ret),
+
+ TP_STRUCT__entry(
+ __field(int, ret)
+ ),
+
+ TP_fast_assign(
+ __entry->ret = ret;
+ ),
+
+ TP_printk("ret=%d", __entry->ret)
+);
+
+DEFINE_EVENT(net_dev_rx_exit_template, napi_gro_frags_exit,
+
+ TP_PROTO(int ret),
+
+ TP_ARGS(ret)
+);
+
+DEFINE_EVENT(net_dev_rx_exit_template, napi_gro_receive_exit,
+
+ TP_PROTO(int ret),
+
+ TP_ARGS(ret)
+);
+
+DEFINE_EVENT(net_dev_rx_exit_template, netif_receive_skb_exit,
+
+ TP_PROTO(int ret),
+
+ TP_ARGS(ret)
+);
+
+DEFINE_EVENT(net_dev_rx_exit_template, netif_rx_exit,
+
+ TP_PROTO(int ret),
+
+ TP_ARGS(ret)
+);
+
+DEFINE_EVENT(net_dev_rx_exit_template, netif_rx_ni_exit,
+
+ TP_PROTO(int ret),
+
+ TP_ARGS(ret)
+);
+
+DEFINE_EVENT(net_dev_rx_exit_template, netif_receive_skb_list_exit,
+
+ TP_PROTO(int ret),
+
+ TP_ARGS(ret)
+);
+
#endif /* _TRACE_NET_H */
/* This part must be outside protection */
diff --git a/net/core/dev.c b/net/core/dev.c
index abe50c424b29..04a6b7100aac 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4527,9 +4527,14 @@ static int netif_rx_internal(struct sk_buff *skb)
int netif_rx(struct sk_buff *skb)
{
+ int ret;
+
trace_netif_rx_entry(skb);
- return netif_rx_internal(skb);
+ ret = netif_rx_internal(skb);
+ trace_netif_rx_exit(ret);
+
+ return ret;
}
EXPORT_SYMBOL(netif_rx);
@@ -4544,6 +4549,7 @@ int netif_rx_ni(struct sk_buff *skb)
if (local_softirq_pending())
do_softirq();
preempt_enable();
+ trace_netif_rx_ni_exit(err);
return err;
}
@@ -5229,9 +5235,14 @@ static void netif_receive_skb_list_internal(struct list_head *head)
*/
int netif_receive_skb(struct sk_buff *skb)
{
+ int ret;
+
trace_netif_receive_skb_entry(skb);
- return netif_receive_skb_internal(skb);
+ ret = netif_receive_skb_internal(skb);
+ trace_netif_receive_skb_exit(ret);
+
+ return ret;
}
EXPORT_SYMBOL(netif_receive_skb);
@@ -5251,9 +5262,12 @@ void netif_receive_skb_list(struct list_head *head)
if (list_empty(head))
return;
- list_for_each_entry(skb, head, list)
- trace_netif_receive_skb_list_entry(skb);
+ if (trace_netif_receive_skb_list_entry_enabled()) {
+ list_for_each_entry(skb, head, list)
+ trace_netif_receive_skb_list_entry(skb);
+ }
netif_receive_skb_list_internal(head);
+ trace_netif_receive_skb_list_exit(0);
}
EXPORT_SYMBOL(netif_receive_skb_list);
@@ -5645,12 +5659,17 @@ static gro_result_t napi_skb_finish(gro_result_t ret, struct sk_buff *skb)
gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
{
+ gro_result_t ret;
+
skb_mark_napi_id(skb, napi);
trace_napi_gro_receive_entry(skb);
skb_gro_reset_offset(skb);
- return napi_skb_finish(dev_gro_receive(napi, skb), skb);
+ ret = napi_skb_finish(dev_gro_receive(napi, skb), skb);
+ trace_napi_gro_receive_exit(ret);
+
+ return ret;
}
EXPORT_SYMBOL(napi_gro_receive);
@@ -5768,6 +5787,7 @@ static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
gro_result_t napi_gro_frags(struct napi_struct *napi)
{
+ gro_result_t ret;
struct sk_buff *skb = napi_frags_skb(napi);
if (!skb)
@@ -5775,7 +5795,10 @@ gro_result_t napi_gro_frags(struct napi_struct *napi)
trace_napi_gro_frags_entry(skb);
- return napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
+ ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
+ trace_napi_gro_frags_exit(ret);
+
+ return ret;
}
EXPORT_SYMBOL(napi_gro_frags);