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net: Convert TCP & DCCP hash tables to use RCU / hlist_nulls

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RCU was added to UDP lookups, using a fast infrastructure :
- sockets kmem_cache use SLAB_DESTROY_BY_RCU and dont pay the
  price of call_rcu() at freeing time.
- hlist_nulls permits to use few memory barriers.

This patch uses same infrastructure for TCP/DCCP established
and timewait sockets.

Thanks to SLAB_DESTROY_BY_RCU, no slowdown for applications
using short lived TCP connections. A followup patch, converting
rwlocks to spinlocks will even speedup this case.

__inet_lookup_established() is pretty fast now we dont have to
dirty a contended cache line (read_lock/read_unlock)

Only established and timewait hashtable are converted to RCU
(bind table and listen table are still using traditional locking)

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2008-11-16 19:40:17 -08:00
committed by David S. Miller
parent 88ab1932ea
commit 3ab5aee7fe
13 changed files with 152 additions and 85 deletions
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4
include/net/inet_hashtables.h
View File

@@ -41,8 +41,8 @@
* I'll experiment with dynamic table growth later.
*/
struct inet_ehash_bucket {
struct hlist_head chain;
struct hlist_head twchain;
struct hlist_nulls_head chain;
struct hlist_nulls_head twchain;
};
/* There are a few simple rules, which allow for local port reuse by

10
include/net/inet_timewait_sock.h
View File

@@ -110,7 +110,7 @@ struct inet_timewait_sock {
#define tw_state __tw_common.skc_state
#define tw_reuse __tw_common.skc_reuse
#define tw_bound_dev_if __tw_common.skc_bound_dev_if
#define tw_node __tw_common.skc_node
#define tw_node __tw_common.skc_nulls_node
#define tw_bind_node __tw_common.skc_bind_node
#define tw_refcnt __tw_common.skc_refcnt
#define tw_hash __tw_common.skc_hash
@@ -137,10 +137,10 @@ struct inet_timewait_sock {
struct hlist_node tw_death_node;
};
static inline void inet_twsk_add_node(struct inet_timewait_sock *tw,
struct hlist_head *list)
static inline void inet_twsk_add_node_rcu(struct inet_timewait_sock *tw,
struct hlist_nulls_head *list)
{
hlist_add_head(&tw->tw_node, list);
hlist_nulls_add_head_rcu(&tw->tw_node, list);
}
static inline void inet_twsk_add_bind_node(struct inet_timewait_sock *tw,
@@ -175,7 +175,7 @@ static inline int inet_twsk_del_dead_node(struct inet_timewait_sock *tw)
}
#define inet_twsk_for_each(tw, node, head) \
hlist_for_each_entry(tw, node, head, tw_node)
hlist_nulls_for_each_entry(tw, node, head, tw_node)
#define inet_twsk_for_each_inmate(tw, node, jail) \
hlist_for_each_entry(tw, node, jail, tw_death_node)