net.inet.tcp.slowstart_flightsize in 8-STABLE

[Lawrence Stewart]

On 11/03/10 09:30, Andre Oppermann wrote:
> On 02.11.2010 01:11, Maxim Dounin wrote:
>> Hello!
>>
>> On Mon, Sep 27, 2010 at 03:17:59PM +0200, Andre Oppermann wrote:
>>
>>> On 27.09.2010 10:12, Maxim Dounin wrote:
>>>> Hello!
>>>>
>>>> On Mon, Sep 13, 2010 at 09:24:53PM +0400, Maxim Dounin wrote:
>>>>
>>>> [...]
>>>>
>>>>> Andre, could you please take a look at one more patch as well?
>>>>>
>>>>> Igor reported that it still sees 100ms delays with rfc3465 turned
>>>>> on, and it turns out to be similar issue (setting cwnd to 1*MSS)
>>>>> for hosts found in hostcache.
>>>>>
>>>>> The problem with setting cwnd from hostcache was already reported
>>>>> here:
>>>>>
>>>>> http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/92690
>>>>> http://lists.freebsd.org/pipermail/freebsd-net/2007-July/014780.html
>>>>>
>>>>> As using larger cwnd from hostcache may cause problems on
>>>>> congested links (see second thread) I changed code to only use
>>>>> cached cwnd as an upper bound for cwnd (instead of fixing current
>>>>> code).  This is also in-line with what we do on connection
>>>>> restarts.
>>>>>
>>>>> We may later consider re-adding usage of larger cwnd from
>>>>> hostcache.  But I believe it should be done carefully and
>>>>> probably behind sysctl, off by default.
>>>>
>>>> Ping.
>>>
>>> Thanks for the reminder.  I'll disable priming CWND from hostcache.
>>
>> Ping again.
>>
>> I would like to see the patch in question[1] committed and MFC'ed
>> somewhere before 8.2.
>>
>> Andre, if you are just too busy to do it yourself - please say so,
>> I'll ask somebody else to commit it.
> 
> Thanks for the reminder.  After EuroBSDCon Developer Summit I was
> busy with other work and most of my tcp work was stalled due to
> review bandwidth issues.

Sorry for the review bandwidth issues. I'm only just managing to keep my
head above water at the moment and have had to reduce much of my FreeBSD
work to a trickle.

> Lawrence, could you please spare a few seconds and take a quick look
> at the attached patch?

The patch looks fine, please commit. I hope to give the hostcache some
TLC at some point, but in the meantime it's fine to ignore cached cwnd.

Cheers,
Lawrence