pkt_sched: fq: fix pacing for small frames
authorEric Dumazet <edumazet@google.com>
Fri, 15 Nov 2013 16:58:14 +0000 (08:58 -0800)
committerDavid S. Miller <davem@davemloft.net>
Sat, 16 Nov 2013 02:01:52 +0000 (21:01 -0500)
commitf52ed89971adbe79b6438c459814034707b8ab91
tree87135c0dc32f5abc284e4298fc674ff7f03d0f16
parent65c5189a2b57b9aa1d89e4b79da39928257c9505
pkt_sched: fq: fix pacing for small frames

For performance reasons, sch_fq tried hard to not setup timers for every
sent packet, using a quantum based heuristic : A delay is setup only if
the flow exhausted its credit.

Problem is that application limited flows can refill their credit
for every queued packet, and they can evade pacing.

This problem can also be triggered when TCP flows use small MSS values,
as TSO auto sizing builds packets that are smaller than the default fq
quantum (3028 bytes)

This patch adds a 40 ms delay to guard flow credit refill.

Fixes: afe4fd062416 ("pkt_sched: fq: Fair Queue packet scheduler")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/uapi/linux/pkt_sched.h
net/sched/sch_fq.c