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>

1 files changed, 1 insertions, 0 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 */