tree 19e12fe1c09bd817cae2410b5dd0b68ff6c21e43
parent 576fd2f7cac3daa36025f0039f9e7cb75b4b4ae0
author Paolo Abeni <pabeni@redhat.com> 1553266915 +0100
committer David S. Miller <davem@davemloft.net> 1553392356 -0400

net: sched: add empty status flag for NOLOCK qdisc

The queue is marked not empty after acquiring the seqlock,
and it's up to the NOLOCK qdisc clearing such flag on dequeue.
Since the empty status lays on the same cache-line of the
seqlock, it's always hot on cache during the updates.

This makes the empty flag update a little bit loosy. Given
the lack of synchronization between enqueue and dequeue, this
is unavoidable.

v2 -> v3:
 - qdisc_is_empty() has a const argument (Eric)

v1 -> v2:
 - use really an 'empty' flag instead of 'not_empty', as
   suggested by Eric

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>