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rps: shortcut net_rps_action()

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net_rps_action() is a bit expensive on NR_CPUS=64..4096 kernels, even if
RPS is not active.

Tom Herbert used two bitmasks to hold information needed to send IPI,
but a single LIFO list seems more appropriate.

Move all RPS logic into net_rps_action() to cleanup net_rx_action() code
(remove two ifdefs)

Move rps_remote_softirq_cpus into softnet_data to share its first cache
line, filling an existing hole.

In a future patch, we could call net_rps_action() from process_backlog()
to make sure we send IPI before handling this cpu backlog.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2010-04-19 05:07:33 +00:00
committed by David S. Miller
parent a03b1a5c95
commit 88751275b8
2 changed files with 38 additions and 50 deletions
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9
include/linux/netdevice.h
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@ -1381,17 +1381,20 @@ static inline int unregister_gifconf(unsigned int family)
}
/*
* Incoming packets are placed on per-cpu queues so that
* no locking is needed.
* Incoming packets are placed on per-cpu queues
*/
struct softnet_data {
struct Qdisc *output_queue;
struct list_head poll_list;
struct sk_buff *completion_queue;
/* Elements below can be accessed between CPUs for RPS */
#ifdef CONFIG_RPS
struct softnet_data *rps_ipi_list;
/* Elements below can be accessed between CPUs for RPS */
struct call_single_data csd ____cacheline_aligned_in_smp;
struct softnet_data *rps_ipi_next;
unsigned int cpu;
unsigned int input_queue_head;
#endif
struct sk_buff_head input_pkt_queue;