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

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 <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
This commit is contained in:
Eric Dumazet 2008-11-16 19:40:17 -08:00 • committed by David S. Miller
commit 3ab5aee7fe
13 changed files with 151 additions and 84 deletions

View file

@ -938,6 +938,7 @@ static struct proto dccp_v4_prot = {
.orphan_count = &dccp_orphan_count,
.max_header = MAX_DCCP_HEADER,
.obj_size = sizeof(struct dccp_sock),
.slab_flags = SLAB_DESTROY_BY_RCU,
.rsk_prot = &dccp_request_sock_ops,
.twsk_prot = &dccp_timewait_sock_ops,
.h.hashinfo = &dccp_hashinfo,

View file

@ -1140,6 +1140,7 @@ static struct proto dccp_v6_prot = {
.orphan_count = &dccp_orphan_count,
.max_header = MAX_DCCP_HEADER,
.obj_size = sizeof(struct dccp6_sock),
.slab_flags = SLAB_DESTROY_BY_RCU,
.rsk_prot = &dccp6_request_sock_ops,
.twsk_prot = &dccp6_timewait_sock_ops,
.h.hashinfo = &dccp_hashinfo,

View file

@ -1090,8 +1090,8 @@ static int __init dccp_init(void)
}
for (i = 0; i < dccp_hashinfo.ehash_size; i++) {
INIT_HLIST_HEAD(&dccp_hashinfo.ehash[i].chain);
INIT_HLIST_HEAD(&dccp_hashinfo.ehash[i].twchain);
INIT_HLIST_NULLS_HEAD(&dccp_hashinfo.ehash[i].chain, i);
INIT_HLIST_NULLS_HEAD(&dccp_hashinfo.ehash[i].twchain, i);
}
if (inet_ehash_locks_alloc(&dccp_hashinfo))