Messages in this thread |  | | From | Dan Kegel <> | Subject | Re: Out of socket memory? (2.4.0-test11) |
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Dan Kegel wrote: > Daniel Walton (zwwe@opti.cgi.net) wrote: > > I've been having a problem with a high volume Linux web server. This > > particular web server used to be a FreeBSD machine and I've been trying to > > successfully make the switch for some time now. I've been trying the 2.4 > > development kernels as they come out and I've been tweaking the /proc > > filesystem variables but so far nothing seems to have fixed the > > problem. The problem is that I get "Out of socket memory" errors and the > > networking locks up... > > FWIW, the code that prints this is in ipv4/tcp_timer.c > and it looks like it's a DoS attack countermeasure. > > /* Do not allow orphaned sockets to eat all our resources. > * This is direct violation of TCP specs, but it is required > * to prevent DoS attacks. It is called when a retransmission timeout > * or zero probe timeout occurs on orphaned socket. > ... > if (orphans >= sysctl_tcp_max_orphans || > (sk->wmem_queued > SOCK_MIN_SNDBUF && > atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])) { > if (net_ratelimit()) > printk(KERN_INFO "Out of socket memory\n");
See Documentation/networking/ip-sysctl.txt for more info and tuning suggestions, esp. tcp_orphan_retries and tcp_max_orphans. An orphaned socket is one that has at least partially opened, but has not been fully accepted. You might try reducing tcp_orphan_retries.
It looks like you can view the current number of orphans at /proc/net/sockstat or something like that.
/* * Report socket allocation statistics [mea@utu.fi] */ int afinet_get_info(char *buffer, char **start, off_t offset, int length) { /* From net/socket.c */ extern int socket_get_info(char *, char **, off_t, int); int len = socket_get_info(buffer,start,offset,length); len += sprintf(buffer+len,"TCP: inuse %d orphan %d tw %d alloc %d mem %d\n", fold_prot_inuse(&tcp_prot), atomic_read(&tcp_orphan_count), tcp_tw_count, atomic_read(&tcp_sockets_allocated), atomic_read(&tcp_memory_allocated));
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