What is the timeout of TCP in freeBSD?

[Karthik Reddy]

When I change the kern.hz to 50, the timeout is happening at 76sec. Could
you please elaborate on kern.hz and how does it effect timing.


On Sun, Jan 20, 2013 at 10:12 PM, Adam Vande More <amvandemore at gmail.com>wrote:

> On Sun, Jan 20, 2013 at 8:50 AM, Karthik Reddy <22karthikreddy at gmail.com>wrote:
>
>> I was doing a experiment on FreeBSD for testing TCP timeout and RTO. OS is
>> being run from two different VMware versions 4.0 and 5.0.
>>
>> Present Scenario: VMware Player 4.0
>> I'll start a telnet session to a non-existing system in the network. When
>> I
>> look at the tcpdump the RTO starts at every 3 seconds and after some
>> exponential backoff starts. In this scenario after 75 seconds the TCP
>> gives
>> up and tells me that there is no system existing with the IP and telnet
>> session terminates.
>>
>> Next Scenario: VMware Player 5.0
>> In this scenario, I did the same but the RTO starts at 5 sec and then
>> varies. In this scenario, it takes more than 120 seconds for telnet
>> session
>> to tell me that there is no system is available in the network.
>>
>> I have seen sysctl in both VM's. net.inet.tcp.keepinit = 75000
>>
>> Is this problem something related to timing of the VM's or any other
>> issue?
>>
>
> What's the wallclock delta during such a test?  Have you tried setting
> 'kern.hz="50"' or fiddling other TC options?  UP VM's tend to keep time
> better than other multicore configs.
>
> --
> Adam Vande More




-- 
Karthik Reddy
I'm not the best, but I'm not like the Rest