[NET]: Size listen hash tables using backlog hint
We currently allocate a fixed size (TCP_SYNQ_HSIZE=512) slots hash table for
each LISTEN socket, regardless of various parameters (listen backlog for
example)
On x86_64, this means order-1 allocations (might fail), even for 'small'
sockets, expecting few connections. On the contrary, a huge server wanting a
backlog of 50000 is slowed down a bit because of this fixed limit.
This patch makes the sizing of listen hash table a dynamic parameter,
depending of :
- net.core.somaxconn tunable (default is 128)
- net.ipv4.tcp_max_syn_backlog tunable (default : 256, 1024 or 128)
- backlog value given by user application (2nd parameter of listen())
For large allocations (bigger than PAGE_SIZE), we use vmalloc() instead of
kmalloc().
We still limit memory allocation with the two existing tunables (somaxconn &
tcp_max_syn_backlog). So for standard setups, this patch actually reduce RAM
usage.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 72cbdcfc..047d170 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -262,12 +262,12 @@
EXPORT_SYMBOL_GPL(dccp_destroy_sock);
-static inline int dccp_listen_start(struct sock *sk)
+static inline int dccp_listen_start(struct sock *sk, int backlog)
{
struct dccp_sock *dp = dccp_sk(sk);
dp->dccps_role = DCCP_ROLE_LISTEN;
- return inet_csk_listen_start(sk, TCP_SYNQ_HSIZE);
+ return inet_csk_listen_start(sk, backlog);
}
int dccp_disconnect(struct sock *sk, int flags)
@@ -788,7 +788,7 @@
* FIXME: here it probably should be sk->sk_prot->listen_start
* see tcp_listen_start
*/
- err = dccp_listen_start(sk);
+ err = dccp_listen_start(sk, backlog);
if (err)
goto out;
}