net-timestamp: SCHED timestamp on entering packet scheduler

Kernel transmit latency is often incurred in the packet scheduler.
Introduce a new timestamp on transmission just before entering the
scheduler. When data travels through multiple devices (bonding,
tunneling, ...) each device will export an individual timestamp.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 3 insertions, 1 deletions

diff --git a/include/uapi/linux/errqueue.h b/include/uapi/linux/errqueue.h
index accee72cae7c..17437cf297b7 100644
--- a/include/uapi/linux/errqueue.h
+++ b/include/uapi/linux/errqueue.h
@@ -39,6 +39,7 @@ struct scm_timestamping {
  */
 enum {
         SCM_TSTAMP_SND,         /* driver passed skb to NIC, or HW */
+        SCM_TSTAMP_SCHED,       /* data entered the packet scheduler */
 };
 
 #endif /* _UAPI_LINUX_ERRQUEUE_H */
diff --git a/include/uapi/linux/net_tstamp.h b/include/uapi/linux/net_tstamp.h
index 1e861d2e1a31..60733845fcdd 100644
--- a/include/uapi/linux/net_tstamp.h
+++ b/include/uapi/linux/net_tstamp.h
@@ -21,8 +21,9 @@ enum {
         SOF_TIMESTAMPING_SYS_HARDWARE = (1<<5),
         SOF_TIMESTAMPING_RAW_HARDWARE = (1<<6),
         SOF_TIMESTAMPING_OPT_ID = (1<<7),
+        SOF_TIMESTAMPING_TX_SCHED = (1<<8),
 
-        SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_ID,
+        SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_TX_SCHED,
         SOF_TIMESTAMPING_MASK = (SOF_TIMESTAMPING_LAST - 1) |
                                  SOF_TIMESTAMPING_LAST
 };