Messages in this thread | | | From | Dan Kegel <> | Subject | Re: Out of socket memory? (2.4.0-test11) |
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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. Looks like you can tune it with sysctl_tcp_max_orphans, among other things. Here's the code from test11-pre4:
/* 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. * * Criterium is still not confirmed experimentally and may change. * We kill the socket, if: * 1. If number of orphaned sockets exceeds an administratively configured * limit. * 2. If we have strong memory pressure. */ static int tcp_out_of_resources(struct sock *sk, int do_reset) { struct tcp_opt *tp = &(sk->tp_pinfo.af_tcp); int orphans = atomic_read(&tcp_orphan_count); /* If peer does not open window for long time, or did not transmit * anything for long time, penalize it. */ if ((s32)(tcp_time_stamp - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset) orphans <<= 1; /* If some dubious ICMP arrived, penalize even more. */ if (sk->err_soft) orphans <<= 1; 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"); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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