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2b77bdde97
Profiles show false sharing in addr_compare() because refcnt/dtime
changes dirty the first inet_peer cache line, where are lying the keys
used at lookup time. If many cpus are calling inet_getpeer() and
inet_putpeer(), or need frag ids, addr_compare() is in 2nd position in
"perf top".
Before patch, my udpflood bench (16 threads) on my 2x4x2 machine :
5784.00 9.7% csum_partial_copy_generic [kernel]
3356.00 5.6% addr_compare [kernel]
2638.00 4.4% fib_table_lookup [kernel]
2625.00 4.4% ip_fragment [kernel]
1934.00 3.2% neigh_lookup [kernel]
1617.00 2.7% udp_sendmsg [kernel]
1608.00 2.7% __ip_route_output_key [kernel]
1480.00 2.5% __ip_append_data [kernel]
1396.00 2.3% kfree [kernel]
1195.00 2.0% kmem_cache_free [kernel]
1157.00 1.9% inet_getpeer [kernel]
1121.00 1.9% neigh_resolve_output [kernel]
1012.00 1.7% dev_queue_xmit [kernel]
# time ./udpflood.sh
real 0m44.511s
user 0m20.020s
sys 11m22.780s
# time ./udpflood.sh
real 0m44.099s
user 0m20.140s
sys 11m15.870s
After patch, no more addr_compare() in profiles :
4171.00 10.7% csum_partial_copy_generic [kernel]
1787.00 4.6% fib_table_lookup [kernel]
1756.00 4.5% ip_fragment [kernel]
1234.00 3.2% udp_sendmsg [kernel]
1191.00 3.0% neigh_lookup [kernel]
1118.00 2.9% __ip_append_data [kernel]
1022.00 2.6% kfree [kernel]
993.00 2.5% __ip_route_output_key [kernel]
841.00 2.2% neigh_resolve_output [kernel]
816.00 2.1% kmem_cache_free [kernel]
658.00 1.7% ia32_sysenter_target [kernel]
632.00 1.6% kmem_cache_alloc_node [kernel]
# time ./udpflood.sh
real 0m41.587s
user 0m19.190s
sys 10m36.370s
# time ./udpflood.sh
real 0m41.486s
user 0m19.290s
sys 10m33.650s
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
117 lines
2.9 KiB
C
117 lines
2.9 KiB
C
/*
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* INETPEER - A storage for permanent information about peers
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*
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* Authors: Andrey V. Savochkin <saw@msu.ru>
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*/
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#ifndef _NET_INETPEER_H
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#define _NET_INETPEER_H
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#include <linux/types.h>
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#include <linux/init.h>
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#include <linux/jiffies.h>
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#include <linux/spinlock.h>
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#include <linux/rtnetlink.h>
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#include <net/ipv6.h>
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#include <asm/atomic.h>
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struct inetpeer_addr_base {
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union {
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__be32 a4;
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__be32 a6[4];
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};
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};
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struct inetpeer_addr {
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struct inetpeer_addr_base addr;
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__u16 family;
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};
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struct inet_peer {
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/* group together avl_left,avl_right,v4daddr to speedup lookups */
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struct inet_peer __rcu *avl_left, *avl_right;
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struct inetpeer_addr daddr;
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__u32 avl_height;
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u32 metrics[RTAX_MAX];
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u32 rate_tokens; /* rate limiting for ICMP */
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unsigned long rate_last;
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unsigned long pmtu_expires;
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u32 pmtu_orig;
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u32 pmtu_learned;
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struct inetpeer_addr_base redirect_learned;
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/*
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* Once inet_peer is queued for deletion (refcnt == -1), following fields
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* are not available: rid, ip_id_count, tcp_ts, tcp_ts_stamp
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* We can share memory with rcu_head to help keep inet_peer small.
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*/
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union {
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struct {
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atomic_t rid; /* Frag reception counter */
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atomic_t ip_id_count; /* IP ID for the next packet */
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__u32 tcp_ts;
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__u32 tcp_ts_stamp;
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};
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struct rcu_head rcu;
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struct inet_peer *gc_next;
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};
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/* following fields might be frequently dirtied */
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__u32 dtime; /* the time of last use of not referenced entries */
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atomic_t refcnt;
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};
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void inet_initpeers(void) __init;
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#define INETPEER_METRICS_NEW (~(u32) 0)
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static inline bool inet_metrics_new(const struct inet_peer *p)
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{
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return p->metrics[RTAX_LOCK-1] == INETPEER_METRICS_NEW;
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}
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/* can be called with or without local BH being disabled */
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struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create);
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static inline struct inet_peer *inet_getpeer_v4(__be32 v4daddr, int create)
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{
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struct inetpeer_addr daddr;
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daddr.addr.a4 = v4daddr;
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daddr.family = AF_INET;
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return inet_getpeer(&daddr, create);
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}
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static inline struct inet_peer *inet_getpeer_v6(const struct in6_addr *v6daddr, int create)
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{
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struct inetpeer_addr daddr;
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ipv6_addr_copy((struct in6_addr *)daddr.addr.a6, v6daddr);
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daddr.family = AF_INET6;
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return inet_getpeer(&daddr, create);
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}
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/* can be called from BH context or outside */
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extern void inet_putpeer(struct inet_peer *p);
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extern bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout);
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/*
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* temporary check to make sure we dont access rid, ip_id_count, tcp_ts,
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* tcp_ts_stamp if no refcount is taken on inet_peer
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*/
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static inline void inet_peer_refcheck(const struct inet_peer *p)
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{
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WARN_ON_ONCE(atomic_read(&p->refcnt) <= 0);
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}
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/* can be called with or without local BH being disabled */
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static inline __u16 inet_getid(struct inet_peer *p, int more)
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{
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more++;
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inet_peer_refcheck(p);
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return atomic_add_return(more, &p->ip_id_count) - more;
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}
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#endif /* _NET_INETPEER_H */
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