netdev - [PATCH net-next v3 05/10] net: qualcomm: rmnet: Set pacing shift

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Message-Id: <1515184884-8242-6-git-send-email-subashab@codeaurora.org>
Date:   Fri,  5 Jan 2018 13:41:19 -0700
From:   Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>
To:     davem@...emloft.net, netdev@...r.kernel.org, lkp@...el.com,
        edumazet@...gle.com
Cc:     Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>
Subject: [PATCH net-next v3 05/10] net: qualcomm: rmnet: Set pacing shift

The real device over which the rmnet devices are installed also
aggregate multiple IP packets and sends them as a single large
aggregate frame to the hardware. This causes degraded throughput
for TCP TX due to bufferbloat.

To overcome this problem, pacing shift value of 8 is set using the
sk_pacing_shift_update() helper. This value was determined based
on experiments with a single stream TCP TX using iperf for a
duration of 30s.

Pacing shift | Observed data rate (Mbps)
          10 | 9
           9 | 140
           8 | 146 (Max link rate)

Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>
---
 drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
index 8e1f43a..8f8c4f2 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
@@ -16,6 +16,7 @@
 #include <linux/netdevice.h>
 #include <linux/netdev_features.h>
 #include <linux/if_arp.h>
+#include <net/sock.h>
 #include "rmnet_private.h"
 #include "rmnet_config.h"
 #include "rmnet_vnd.h"
@@ -204,6 +205,8 @@ void rmnet_egress_handler(struct sk_buff *skb)
 	struct rmnet_priv *priv;
 	u8 mux_id;
 
+	sk_pacing_shift_update(skb->sk, 8);
+
 	orig_dev = skb->dev;
 	priv = netdev_priv(orig_dev);
 	skb->dev = priv->real_dev;
-- 
1.9.1