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[NET]: Size listen hash tables using backlog hint

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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>
This commit is contained in:
Eric Dumazet 2006-11-16 02:30:37 -08:00 • committed by David S. Miller
parent 3c62f75aac
commit 72a3effaf6
9 changed files with 38 additions and 24 deletions
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6
net/ipv4/tcp_ipv4.c
View file

@ -715,7 +715,7 @@ static struct ip_options *tcp_v4_save_options(struct sock *sk,
return dopt;
}
struct request_sock_ops tcp_request_sock_ops = {
struct request_sock_ops tcp_request_sock_ops __read_mostly = {
.family = PF_INET,
.obj_size = sizeof(struct tcp_request_sock),
.rtx_syn_ack = tcp_v4_send_synack,
@ -1385,7 +1385,7 @@ static void *listening_get_next(struct seq_file *seq, void *cur)
if (st->state == TCP_SEQ_STATE_OPENREQ) {
struct request_sock *req = cur;
icsk = inet_csk(st->syn_wait_sk);
icsk = inet_csk(st->syn_wait_sk);
req = req->dl_next;
while (1) {
while (req) {
@ -1395,7 +1395,7 @@ static void *listening_get_next(struct seq_file *seq, void *cur)
}
req = req->dl_next;
}
if (++st->sbucket >= TCP_SYNQ_HSIZE)
if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
break;
get_req:
req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];