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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
net/ipv4/tcp.c
View file

@ -2707,8 +2707,8 @@ void __init tcp_init(void)
thash_entries ? 0 : 512 * 1024);
tcp_hashinfo.ehash_size = 1 << tcp_hashinfo.ehash_size;
for (i = 0; i < tcp_hashinfo.ehash_size; i++) {
INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].chain);
INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].twchain);
INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].chain, i);
INIT_HLIST_NULLS_HEAD(&tcp_hashinfo.ehash[i].twchain, i);
}
if (inet_ehash_locks_alloc(&tcp_hashinfo))
panic("TCP: failed to alloc ehash_locks");