Re: [bug] stuck localhost TCP connections, v2.6.26-rc3+

Ingo Molnar
2008-05-30T18:19:20Z

* Ingo Molnar <mingo@elte.hu> wrote:

> after about 50 bootups i got a hung test again:
>
> titan:~/tip> netstat -nt
> Active Internet connections (w/o servers)
> Proto Recv-Q Send-Q Local Address Foreign Address
> State
> tcp 0 0 10.0.1.14:22 10.0.1.16:58062 ESTABLISHED
> tcp 0 0 10.0.1.14:22 10.0.1.16:60109 ESTABLISHED
> tcp 0 86368 10.0.1.14:43914 10.0.1.16:3632 ESTABLISHED
>
> and this time with CUBIC_TCP disabled - so that was a red herring.

ah, in retrospect i realized that this test had one flaw: some of the
systems i the build cluster already ran a newer kernel and hence were
targets for this bug.

so i turned off CONFIG_TCP_CONG_CUBIC on all the testboxes and rebooted
the cluster boxes into 2.6.25, and the hung sockets are now gone. (about
150 successful iterations)

i did another change as well: i removed the localhost distcc component.
I'll reinstate that now to make sure it's really related to
TCP_CONG_CUBIC and not to localhost networking.

Ingo