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| author | Eric Dumazet <dada1@cosmosbay.com> | 2007-11-07 02:40:20 -0800 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2007-11-07 04:15:11 -0800 |
| commit | 230140cffa7feae90ad50bf259db1fa07674f3a7 (patch) | |
| tree | 815472add31606423a508a17806b7884f0ab3e2e /net/ipv4/inet_hashtables.c | |
| parent | efac52762b1e3fe3035d29e82d8ee1aebc45e4a7 (diff) | |
| download | linux-stable-230140cffa7feae90ad50bf259db1fa07674f3a7.tar.gz linux-stable-230140cffa7feae90ad50bf259db1fa07674f3a7.tar.bz2 linux-stable-230140cffa7feae90ad50bf259db1fa07674f3a7.zip | |
[INET]: Remove per bucket rwlock in tcp/dccp ehash table.
As done two years ago on IP route cache table (commit
22c047ccbc68fa8f3fa57f0e8f906479a062c426) , we can avoid using one
lock per hash bucket for the huge TCP/DCCP hash tables.
On a typical x86_64 platform, this saves about 2MB or 4MB of ram, for
litle performance differences. (we hit a different cache line for the
rwlock, but then the bucket cache line have a better sharing factor
among cpus, since we dirty it less often). For netstat or ss commands
that want a full scan of hash table, we perform fewer memory accesses.
Using a 'small' table of hashed rwlocks should be more than enough to
provide correct SMP concurrency between different buckets, without
using too much memory. Sizing of this table depends on
num_possible_cpus() and various CONFIG settings.
This patch provides some locking abstraction that may ease a future
work using a different model for TCP/DCCP table.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/inet_hashtables.c')
| -rw-r--r-- | net/ipv4/inet_hashtables.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index 16eecc7046a3..67704da04fc4 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -204,12 +204,13 @@ static int __inet_check_established(struct inet_timewait_death_row *death_row, const __portpair ports = INET_COMBINED_PORTS(inet->dport, lport); unsigned int hash = inet_ehashfn(daddr, lport, saddr, inet->dport); struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash); + rwlock_t *lock = inet_ehash_lockp(hinfo, hash); struct sock *sk2; const struct hlist_node *node; struct inet_timewait_sock *tw; prefetch(head->chain.first); - write_lock(&head->lock); + write_lock(lock); /* Check TIME-WAIT sockets first. */ sk_for_each(sk2, node, &head->twchain) { @@ -239,7 +240,7 @@ unique: BUG_TRAP(sk_unhashed(sk)); __sk_add_node(sk, &head->chain); sock_prot_inc_use(sk->sk_prot); - write_unlock(&head->lock); + write_unlock(lock); if (twp) { *twp = tw; @@ -255,7 +256,7 @@ unique: return 0; not_unique: - write_unlock(&head->lock); + write_unlock(lock); return -EADDRNOTAVAIL; } |