TCP RTO

[Thomas Haller]

On Thu, 2016-08-25 at 23:30 +0700, slav agafs wrote:
> Hi,
> 
> I`ve noticed too long TCP RTO (retransmission time out) in some
> situations. Sometimes it can reach 200ms it is too long for my
> application. I could change with no so stright way like this "ip
> route
> change default via 10.0.2.2 dev eth0 rto_min 5ms", but its no so
> quite
> suitable because its small device with no large filesystem for all
> this utils (iproute2) usual I have only busybox and very bad way call
> external program for such appliance. I need  change RTO with libnl
> because I have it linked with my application already. But I cant find
> documented way for that. Please make me hint to support such function
> if there is no ready solution.
> 

Hi,

looking at the source of iproute2, it seems that rto_min sets the
RTAX_RTO_MIN netlink attribute.

libnl-route-3.so currently does not support setting that flag.
So, one way could be to extend the library with that feature.

Otherwise, libnl-3.so gives you full access to the netlink attributes,
so it would be possible to configure what you want. Basically, you'd
create a netlink message like iproute2 does and send it to kernel. But
that would require some effort...


Thomas
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