Re: The rc.d mess strikes back

On Sun, Mar 08, 2009 at 01:02:12PM +0300, Mike Makonnen wrote:
> Brooks Davis wrote:
>> On Wed, Mar 04, 2009 at 12:04:06AM -0800, Garrett Cooper wrote:
>>> On Tue, Mar 3, 2009 at 10:12 PM, Mike Telahun Makonnen
>>> <mmakonnen_at_gmail.com> wrote:
>>>> On Tue, Mar 3, 2009 at 9:03 PM, Brooks Davis <brooks_at_freebsd.org> wrote:
>>>>> I don't have much time to debug this, but I've not had problems with
>>>>> services starting too early on the systems I've been running with async
>>>>> dhcp. ?If there is a problem with the wait process we need to actually
>>>>> debug it. ?If the wait for a route/running interface isn't sufficent we
>>>>> should try to figure out what is. ?Synchronous dhcp sucks and yeilds
>>>>> justifed user complaints so it would be nice to kill it off. ?I switched
>>>>> the default because it worked for me and I hoped that people would help
>>>>> find and fix edge cases.
>>>> Can you elaborate why synchronous DHCP sucks ?
>>> The only reason I could see is bringup time. Am I correct in this assumption?
>> 
>> If you use synchronous DHCP then every interface that wants to try to
>> get a DHCP address if it has link needs to run through the full link
>> timeout at boot.  On a laptop this is annoying and generally pointless.
> 
> Ok, I just turned synchronous dhclient on locally and I see what you
> mean.
> 
>> The changes to defaultroute to wait for a default route to be set mean
>> that you consolidate the wait in one location and you don't waste time
>> starting dhclient on interfaces until a link exists (or an association
>> is made for wlan devices).
> 
> OK, so that means that it's not just waiting for the default route, but
> it's also waiting for the link on any DHCP interfaces to come up as
> well. That's what confused me. When it's plugged in my NIC's link is
> always up by the time rc.d gets to the default route, so I didn't see
> the point in waiting the extra 30sec when it wasn't plugged in. The
> comments also seemed to imply that we should be checking whether the
> link is up.
> 
> Anyways, given that synchronous dhclient re-introduces the same problem
> I was trying to fix in the first place I'll just back the whole thing out 
> until we can come up with a better fix. Do you mind if I change the timeout 
> to 15sec. (instead of 30s)?

15 is probably a bit short in practice for wpa networks.  Someone a
while back suggested that there's some reason (perhaps spanning tree,
but I can't remember) why it it should be closer to 50sec for maximum
reliability.  One thing I've thought of adding is changing the sleeps to
"read -t1", checking for a non-timeout result and adding "Press return
to skip".  Another option would be for each interface to set a minimum
timeout based on it's type such as having WPA interfaces set it to 30
and others set it to 15.

-- Brooks