tcp: change default tcp hash size

As time passed, available memory increased faster than number of
concurrent tcp sockets.

As a result, a machine with 4GB of ram gets a hash table
with 524288 slots, using 8388608 bytes of memory.

Lets change that by a 16x factor (one slot for 128 KB of ram)

Even if a small machine needs a _lot_ of sockets, tcp lookups are now
very efficient, using one cache line per socket.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 4 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index e6eace1c2bdb..1aca02c9911e 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3590,8 +3590,7 @@ void __init tcp_init(void)
                 alloc_large_system_hash("TCP established",
                                         sizeof(struct inet_ehash_bucket),
                                         thash_entries,
-                                        (totalram_pages >= 128 * 1024) ?
-                                        13 : 15,
+                                        17, /* one slot per 128 KB of memory */
                                         0,
                                         NULL,
                                         &tcp_hashinfo.ehash_mask,
@@ -3607,8 +3606,7 @@ void __init tcp_init(void)
                 alloc_large_system_hash("TCP bind",
                                         sizeof(struct inet_bind_hashbucket),
                                         tcp_hashinfo.ehash_mask + 1,
-                                        (totalram_pages >= 128 * 1024) ?
-                                        13 : 15,
+                                        17, /* one slot per 128 KB of memory */
                                         0,
                                         &tcp_hashinfo.bhash_size,
                                         NULL,