kernel: backport upstream DSA GRO support
Should improve performance Signed-off-by: Felix Fietkau <nbd@nbd.name>master
Felix Fietkau
4 years ago
parent
dfd62e575c
commit
2c82862068
@ -0,0 +1,143 @@
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From: Alexander Lobakin <bloodyreaper@yandex.ru>
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Date: Tue, 21 Apr 2020 16:41:08 +0300
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Subject: [PATCH] net: dsa: add GRO support via gro_cells
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gro_cells lib is used by different encapsulating netdevices, such as
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geneve, macsec, vxlan etc. to speed up decapsulated traffic processing.
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CPU tag is a sort of "encapsulation", and we can use the same mechs to
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greatly improve overall DSA performance.
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skbs are passed to the GRO layer after removing CPU tags, so we don't
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need any new packet offload types as it was firstly proposed by me in
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the first GRO-over-DSA variant [1].
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The size of struct gro_cells is sizeof(void *), so hot struct
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dsa_slave_priv becomes only 4/8 bytes bigger, and all critical fields
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remain in one 32-byte cacheline.
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The other positive side effect is that drivers for network devices
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that can be shipped as CPU ports of DSA-driven switches can now use
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napi_gro_frags() to pass skbs to kernel. Packets built that way are
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completely non-linear and are likely being dropped without GRO.
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This was tested on to-be-mainlined-soon Ethernet driver that uses
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napi_gro_frags(), and the overall performance was on par with the
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variant from [1], sometimes even better due to minimal overhead.
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net.core.gro_normal_batch tuning may help to push it to the limit
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on particular setups and platforms.
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iperf3 IPoE VLAN NAT TCP forwarding (port1.218 -> port0) setup
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on 1.2 GHz MIPS board:
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5.7-rc2 baseline:
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[ID] Interval Transfer Bitrate Retr
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[ 5] 0.00-120.01 sec 9.00 GBytes 644 Mbits/sec 413 sender
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[ 5] 0.00-120.00 sec 8.99 GBytes 644 Mbits/sec receiver
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Iface RX packets TX packets
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eth0 7097731 7097702
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port0 426050 6671829
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port1 6671681 425862
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port1.218 6671677 425851
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With this patch:
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[ID] Interval Transfer Bitrate Retr
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[ 5] 0.00-120.01 sec 12.2 GBytes 870 Mbits/sec 122 sender
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[ 5] 0.00-120.00 sec 12.2 GBytes 870 Mbits/sec receiver
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Iface RX packets TX packets
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eth0 9474792 9474777
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port0 455200 353288
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port1 9019592 455035
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port1.218 353144 455024
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v2:
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- Add some performance examples in the commit message;
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- No functional changes.
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[1] https://lore.kernel.org/netdev/20191230143028.27313-1-alobakin@dlink.ru/
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Signed-off-by: Alexander Lobakin <bloodyreaper@yandex.ru>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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--- a/net/dsa/Kconfig
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+++ b/net/dsa/Kconfig
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@@ -9,6 +9,7 @@ menuconfig NET_DSA
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tristate "Distributed Switch Architecture"
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depends on HAVE_NET_DSA
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depends on BRIDGE || BRIDGE=n
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+ select GRO_CELLS
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select NET_SWITCHDEV
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select PHYLINK
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select NET_DEVLINK
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--- a/net/dsa/dsa.c
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+++ b/net/dsa/dsa.c
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@@ -238,7 +238,7 @@ static int dsa_switch_rcv(struct sk_buff
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if (dsa_skb_defer_rx_timestamp(p, skb))
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return 0;
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- netif_receive_skb(skb);
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+ gro_cells_receive(&p->gcells, skb);
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return 0;
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}
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--- a/net/dsa/dsa_priv.h
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+++ b/net/dsa/dsa_priv.h
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@@ -11,6 +11,7 @@
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#include <linux/netdevice.h>
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#include <linux/netpoll.h>
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#include <net/dsa.h>
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+#include <net/gro_cells.h>
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enum {
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DSA_NOTIFIER_AGEING_TIME,
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@@ -68,6 +69,8 @@ struct dsa_slave_priv {
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struct pcpu_sw_netstats *stats64;
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+ struct gro_cells gcells;
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+
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/* DSA port data, such as switch, port index, etc. */
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struct dsa_port *dp;
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--- a/net/dsa/slave.c
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+++ b/net/dsa/slave.c
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@@ -1431,6 +1431,11 @@ int dsa_slave_create(struct dsa_port *po
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free_netdev(slave_dev);
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return -ENOMEM;
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}
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+
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+ ret = gro_cells_init(&p->gcells, slave_dev);
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+ if (ret)
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+ goto out_free;
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+
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p->dp = port;
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INIT_LIST_HEAD(&p->mall_tc_list);
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INIT_WORK(&port->xmit_work, dsa_port_xmit_work);
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@@ -1443,7 +1448,7 @@ int dsa_slave_create(struct dsa_port *po
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ret = dsa_slave_phy_setup(slave_dev);
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if (ret) {
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netdev_err(master, "error %d setting up slave phy\n", ret);
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- goto out_free;
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+ goto out_gcells;
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}
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dsa_slave_notify(slave_dev, DSA_PORT_REGISTER);
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@@ -1462,6 +1467,8 @@ out_phy:
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phylink_disconnect_phy(p->dp->pl);
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rtnl_unlock();
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phylink_destroy(p->dp->pl);
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+out_gcells:
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+ gro_cells_destroy(&p->gcells);
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out_free:
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free_percpu(p->stats64);
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free_netdev(slave_dev);
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@@ -1482,6 +1489,7 @@ void dsa_slave_destroy(struct net_device
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dsa_slave_notify(slave_dev, DSA_PORT_UNREGISTER);
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unregister_netdev(slave_dev);
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phylink_destroy(dp->pl);
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+ gro_cells_destroy(&p->gcells);
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free_percpu(p->stats64);
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free_netdev(slave_dev);
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}
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