[PATCH net-next 3/3] tun: introduce cpu id based steering policy
From: Jason Wang <jasowang@redhat.com>
Date: 2017-09-27 08:24:33
Also in:
lkml
Subsystem:
networking drivers, the rest, tun/tap driver · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Willem de Bruijn, Jason Wang
This patch introduces a simple queue selection policy which just choose txq based on processor id. This maybe useful for connectless workload or #queues is equal to #cpus. Redirect UDP packets generated by MoonGen between two virtio-net ports through xdp_redirect show 37.4% (from 0.8Mpps to 1.1Mpps) improvement compared to automatic steering policy since the overhead of flow caches/hasing was totally eliminated. Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/net/tun.c | 33 ++++++++++++++++++++++++++++++++- include/uapi/linux/if_tun.h | 1 + 2 files changed, 33 insertions(+), 1 deletion(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 1106521..03b4506 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c@@ -190,6 +190,20 @@ struct tun_steering_ops { u32 data); }; +void tun_steering_xmit_nop(struct tun_struct *tun, struct sk_buff *skb) +{ +} + +u32 tun_steering_pre_rx_nop(struct tun_struct *tun, struct sk_buff *skb) +{ + return 0; +} + +void tun_steering_post_rx_nop(struct tun_struct *tun, struct tun_file *tfile, + u32 data) +{ +} + struct tun_flow_entry { struct hlist_node hash_link; struct rcu_head rcu;
@@ -571,6 +585,11 @@ static u16 tun_automq_select_queue(struct tun_struct *tun, struct sk_buff *skb) return txq; } +static u16 tun_cpu_select_queue(struct tun_struct *tun, struct sk_buff *skb) +{ + return smp_processor_id() % tun->numqueues; +} + static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb, void *accel_priv, select_queue_fallback_t fallback) {
@@ -2152,6 +2171,13 @@ static struct tun_steering_ops tun_automq_ops = { .post_rx = tun_automq_post_rx, }; +static struct tun_steering_ops tun_cpu_ops = { + .select_queue = tun_cpu_select_queue, + .xmit = tun_steering_xmit_nop, + .pre_rx = tun_steering_pre_rx_nop, + .post_rx = tun_steering_post_rx_nop, +}; + static int tun_flags(struct tun_struct *tun) { return tun->flags & (TUN_FEATURES | IFF_PERSIST | IFF_TUN | IFF_TAP);
@@ -2775,6 +2801,9 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd, case TUN_STEERING_AUTOMQ: tun->steering_ops = &tun_automq_ops; break; + case TUN_STEERING_CPU: + tun->steering_ops = &tun_cpu_ops; + break; default: ret = -EFAULT; }
@@ -2784,6 +2813,8 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd, ret = 0; if (tun->steering_ops == &tun_automq_ops) steering = TUN_STEERING_AUTOMQ; + else if (tun->steering_ops == &tun_cpu_ops) + steering = TUN_STEERING_CPU; else BUG(); if (copy_to_user(argp, &steering, sizeof(steering)))
@@ -2792,7 +2823,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd, case TUNGETSTEERINGFEATURES: ret = 0; - steering = TUN_STEERING_AUTOMQ; + steering = TUN_STEERING_AUTOMQ | TUN_STEERING_CPU; if (copy_to_user(argp, &steering, sizeof(steering))) ret = -EFAULT; break;
diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h
index 109760e..5f71d29 100644
--- a/include/uapi/linux/if_tun.h
+++ b/include/uapi/linux/if_tun.h@@ -112,5 +112,6 @@ struct tun_filter { }; #define TUN_STEERING_AUTOMQ 0x01 /* Automatic flow steering */ +#define TUN_STEERING_CPU 0x02 /* Processor id based flow steering */ #endif /* _UAPI__IF_TUN_H */
--
2.7.4