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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-11-17 03:13:26 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-11-17 17:06:08 -0500 |
| commit | adc9300e78e6091a7eaa1821213836379d4dbaa8 (patch) | |
| tree | b2d075990b32e8c21129851bf1b1adf4cdc441f1 /net/core/dev.c | |
| parent | d6f144830bdfa5fcf116e9ab8fc6a60d23fa623d (diff) | |
| download | lwn-adc9300e78e6091a7eaa1821213836379d4dbaa8.tar.gz lwn-adc9300e78e6091a7eaa1821213836379d4dbaa8.zip | |
net: use jump_label to shortcut RPS if not setup
Most machines dont use RPS/RFS, and pay a fair amount of instructions in
netif_receive_skb() / netif_rx() / get_rps_cpu() just to discover
RPS/RFS is not setup.
Add a jump_label named rps_needed.
If no device rps_map or global rps_sock_flow_table is setup,
netif_receive_skb() / netif_rx() do a single instruction instead of many
ones, including conditional jumps.
jmp +0 (if CONFIG_JUMP_LABEL=y)
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/dev.c')
| -rw-r--r-- | net/core/dev.c | 21 |
1 files changed, 9 insertions, 12 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 26c49d55e79d..f78959996148 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2711,6 +2711,8 @@ EXPORT_SYMBOL(__skb_get_rxhash); struct rps_sock_flow_table __rcu *rps_sock_flow_table __read_mostly; EXPORT_SYMBOL(rps_sock_flow_table); +struct jump_label_key rps_needed __read_mostly; + static struct rps_dev_flow * set_rps_cpu(struct net_device *dev, struct sk_buff *skb, struct rps_dev_flow *rflow, u16 next_cpu) @@ -2994,7 +2996,7 @@ int netif_rx(struct sk_buff *skb) trace_netif_rx(skb); #ifdef CONFIG_RPS - { + if (static_branch(&rps_needed)) { struct rps_dev_flow voidflow, *rflow = &voidflow; int cpu; @@ -3009,14 +3011,13 @@ int netif_rx(struct sk_buff *skb) rcu_read_unlock(); preempt_enable(); - } -#else + } else +#endif { unsigned int qtail; ret = enqueue_to_backlog(skb, get_cpu(), &qtail); put_cpu(); } -#endif return ret; } EXPORT_SYMBOL(netif_rx); @@ -3359,7 +3360,7 @@ int netif_receive_skb(struct sk_buff *skb) return NET_RX_SUCCESS; #ifdef CONFIG_RPS - { + if (static_branch(&rps_needed)) { struct rps_dev_flow voidflow, *rflow = &voidflow; int cpu, ret; @@ -3370,16 +3371,12 @@ int netif_receive_skb(struct sk_buff *skb) if (cpu >= 0) { ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail); rcu_read_unlock(); - } else { - rcu_read_unlock(); - ret = __netif_receive_skb(skb); + return ret; } - - return ret; + rcu_read_unlock(); } -#else - return __netif_receive_skb(skb); #endif + return __netif_receive_skb(skb); } EXPORT_SYMBOL(netif_receive_skb); |