From: Phil Sutter <phil@nwl.cc>
To: netdev@vger.kernel.org
Cc: Jesper Dangaard Brouer <brouer@redhat.com>,
Cong Wang <cwang@twopensource.com>,
Eric Dumazet <eric.dumazet@gmail.com>,
David Miller <davem@davemloft.net>
Subject: [net-next PATCH 2/3] net: sched: set tx_queue_len to default when changing noqueue device's qdisc
Date: Wed, 29 Jul 2015 22:51:42 +0200 [thread overview]
Message-ID: <1438203103-27013-3-git-send-email-phil@nwl.cc> (raw)
In-Reply-To: <1438203103-27013-2-git-send-email-phil@nwl.cc>
Virtual interfaces don't necessarily need a qdisc attached to them. This
is signalled by setting dev->tx_queue_len to zero upon initialisation. The
problems begin when a user still adds a qdisc, as then the special value
is used as a regular one causing massive packet drops as soon as the
device sees a bit of traffic load.
This patch solves the issue by setting tx_queue_len to the global
default for physical devices if it is zero and a qdisc is added. Another
benefit of this is that veth devices can default to noqueue while still
preserving the expected behaviour when adding a qdisc.
The drawback of this patch is that the noqueue state won't be restored
after a user has removed the custom qdisc, as the information about
whether this is legitimate for the given device is lost.
Signed-off-by: Phil Sutter <phil@nwl.cc>
---
net/sched/sch_api.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index f06aa01..79b8900 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1315,6 +1315,10 @@ graft:
qdisc_destroy(q);
return err;
}
+ /* circumvent noqueue hack for virtual interfaces if
+ * user desires to use a qdisc on it */
+ if (!dev->tx_queue_len)
+ dev->tx_queue_len = CONFIG_DEFAULT_TX_QUEUE_LEN;
return 0;
}
--
2.1.2
next prev parent reply other threads:[~2015-07-29 20:51 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-29 20:51 [net-next PATCH 0/3] Backwards-compatible noqueue in virtual interfaces Phil Sutter
2015-07-29 20:51 ` [net-next PATCH 1/3] net: make default tx_queue_len configurable Phil Sutter
2015-07-29 20:51 ` Phil Sutter [this message]
2015-07-29 20:51 ` [net-next PATCH 3/3] veth: don't assign a qdisc to veth Phil Sutter
2015-07-29 21:10 ` [net-next PATCH 2/3] net: sched: set tx_queue_len to default when changing noqueue device's qdisc Florian Westphal
2015-07-29 21:10 ` Eric Dumazet
2015-07-29 22:08 ` Phil Sutter
2015-07-29 21:06 ` [net-next PATCH 1/3] net: make default tx_queue_len configurable Florian Westphal
2015-07-29 21:34 ` Phil Sutter
2015-07-29 21:37 ` David Miller
2015-08-11 15:48 ` Jesper Dangaard Brouer
2015-08-11 16:23 ` Phil Sutter
2015-08-12 1:13 ` Alexei Starovoitov
2015-08-12 14:55 ` Eric Dumazet
2015-08-13 1:13 ` Phil Sutter
2015-08-13 13:10 ` Jesper Dangaard Brouer
2015-08-13 15:06 ` Phil Sutter
2015-07-29 23:10 ` [net-next PATCH 0/3] Backwards-compatible noqueue in virtual interfaces Cong Wang
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