From d6f938ce52f9adb23f4c31cc371654a5f18ff328 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 13 May 2022 11:34:05 -0700 Subject: [PATCH] net: loopback: enable BIG TCP packets Set the driver limit to GSO_MAX_SIZE (512 KB). This allows the admin/user to set a GSO limit up to this value. Tested: ip link set dev lo gso_max_size 200000 netperf -H ::1 -t TCP_RR -l 100 -- -r 80000,80000 & tcpdump shows : 18:28:42.962116 IP6 ::1 > ::1: HBH 40051 > 63780: Flags [P.], seq 3626480001:3626560001, ack 3626560001, win 17743, options [nop,nop,TS val 3771179265 ecr 3771179265], length 80000 18:28:42.962138 IP6 ::1.63780 > ::1.40051: Flags [.], ack 3626560001, win 17743, options [nop,nop,TS val 3771179265 ecr 3771179265], length 0 18:28:42.962152 IP6 ::1 > ::1: HBH 63780 > 40051: Flags [P.], seq 3626560001:3626640001, ack 3626560001, win 17743, options [nop,nop,TS val 3771179265 ecr 3771179265], length 80000 18:28:42.962157 IP6 ::1.40051 > ::1.63780: Flags [.], ack 3626640001, win 17743, options [nop,nop,TS val 3771179265 ecr 3771179265], length 0 18:28:42.962180 IP6 ::1 > ::1: HBH 40051 > 63780: Flags [P.], seq 3626560001:3626640001, ack 3626640001, win 17743, options [nop,nop,TS val 3771179265 ecr 3771179265], length 80000 18:28:42.962214 IP6 ::1.63780 > ::1.40051: Flags [.], ack 3626640001, win 17743, options [nop,nop,TS val 3771179266 ecr 3771179265], length 0 18:28:42.962228 IP6 ::1 > ::1: HBH 63780 > 40051: Flags [P.], seq 3626640001:3626720001, ack 3626640001, win 17743, options [nop,nop,TS val 3771179266 ecr 3771179265], length 80000 18:28:42.962233 IP6 ::1.40051 > ::1.63780: Flags [.], ack 3626720001, win 17743, options [nop,nop,TS val 3771179266 ecr 3771179266], length 0 Signed-off-by: Eric Dumazet Acked-by: Alexander Duyck Signed-off-by: David S. Miller --- drivers/net/loopback.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c index 720394c0639b..14e8d04cb434 100644 --- a/drivers/net/loopback.c +++ b/drivers/net/loopback.c @@ -191,6 +191,8 @@ static void gen_lo_setup(struct net_device *dev, dev->netdev_ops = dev_ops; dev->needs_free_netdev = true; dev->priv_destructor = dev_destructor; + + netif_set_tso_max_size(dev, GSO_MAX_SIZE); } /* The loopback device is special. There is only one instance -- 2.11.0