Re: [Qemu-devel] PATCH: enabling TCP keepalives - v3

[David Ahern <dsahern@gmail.com>]

Paul Brook wrote:
>> I don't think an option is very useful.  If you lose your connection and
>> now have a bunch of orphan connections, it's too late to have the
>> foresight to have used an option on startup.  In that case, it would be
>> much better to just be able to close existing connections.
>>
>> I think there's a very, very small number of people that would have the
>> foresight to always use keepalive=60 or whatever the option would be.
> 
> In that case we should do nothing. Users with a flakey net connection can 
> tweak their kernel (via /proc/sys) to use lower timeouts. AFAICS There's no 
> way qemu can know what a "better" value is. As a concrete example my ADSL 
> connection takes between 90 and 180 seconds to resync after a noise spike, so 
> 60 seconds is absolutely the wrong timeout value here.
> 
> Paul

ie., just enable keepalives and use OS defaults? The linux default is
7200 seconds to start sending probes (which is 2 hours as Avi noted, not
7 hours as I misstated).

I'll send an updated patch.

david