Updates using idle bandwidth

Sunil Ghai sunilkrghai at gmail.com
Wed Mar 26 13:32:09 UTC 2008


On Wed, Mar 26, 2008 at 8:48 AM, Les Mikesell <lesmikesell at gmail.com> wrote:

> Tomasz Torcz wrote:
> >
> >>  > Module tcp_lp.ko will be autoloaded by kernel. So this setsockopt()
> call
> >>  > is ready to be put into yum-updatesd, just after socket creation.
> >>
>

> >> A good question then is how do you set congestion level off and not get
> the
> >> kernel module loaded (if its not needed you wouldn't want it loading
> just to
> >> have it do nothing).  Does setting TCP_CONGESTION = 0 result in not
> loading the
> >> module or does it just not limit traffic?
> >
> >   That's not how it works. TCP has mechanisms for dealing with congested
> > links. There is *always* some algorithm present in TCP stack which
> > manipulates connection parameters to not overflow links. By default its
> > reno (or cubic), but Linux kernel provides several others to *choose*
> > from. This isn't a question of turning limiting ON or OFF.
> >
> >  Anyway, after some more reading I see that TCP Low Priority is
> > sender-side algorithm. I don not know if sending ACKs is impacted by
> > congestion algorithms, and this is only thing for client to modify
>

>
> Yes, yum is mostly receiving.  An application can control receive
> bandwidth simply by rate-limiting its reads from the socket, but it will
> have no idea what an appropriate rate might be.


Won't this *dynamic* rate-limiting be decided by TCP-LP congestion control
mechanism to use only idle bandwidth?  And could someone tell me what
problems I might face if I make it to work with yum?

Thanks.

PS: I am really new to this, please forgive me if any question asked doesn't
make sense. :)

-- 
Regards,
Sunil Ghai
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