netdev - [PATCH 5/5] batman-adv: Enable LockLess TX for softif

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Message-Id: <20180919123238.23742-6-sw@simonwunderlich.de>
Date:   Wed, 19 Sep 2018 14:32:38 +0200
From:   Simon Wunderlich <sw@...onwunderlich.de>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, b.a.t.m.a.n@...ts.open-mesh.org,
        Sven Eckelmann <sven@...fation.org>,
        Simon Wunderlich <sw@...onwunderlich.de>
Subject: [PATCH 5/5] batman-adv: Enable LockLess TX for softif

From: Sven Eckelmann <sven@...fation.org>

The batadv interfaces are virtual interfaces which just tunnel the traffic
over other ethernet compatible interfaces. It doesn't need serialization
during the tx phase and is using RCU for most of its internal
datastructures. Since it doesn't have actual queues which could be locked
independently, the throughput gets significantly reduced by the extra lock
in the core net code.

8 parallel TCP connections forwarded by an IPQ4019 based hardware over
5GHz could reach:

* without LLTX: 349 Mibit/s
* with LLTX:    563 Mibit/s

Signed-off-by: Sven Eckelmann <sven@...fation.org>
Signed-off-by: Simon Wunderlich <sw@...onwunderlich.de>
---
 net/batman-adv/soft-interface.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index e121c59fc1fa..2c7d95727f90 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -1050,6 +1050,7 @@ static void batadv_softif_init_early(struct net_device *dev)
 	dev->needs_free_netdev = true;
 	dev->priv_destructor = batadv_softif_free;
 	dev->features |= NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_NETNS_LOCAL;
+	dev->features |= NETIF_F_LLTX;
 	dev->priv_flags |= IFF_NO_QUEUE;
 
 	/* can't call min_mtu, because the needed variables
-- 
2.11.0