Re: Network cooling device and how to control NIC speed on thermal condition

From	Andrew Lunn <andrew@lunn.ch>
Newsgroups	linux.kernel
Subject	Re: Network cooling device and how to control NIC speed on thermal condition
Date	2017-05-08 16:10 +0200
Message-ID	<tERwm-4V1-19@gated-at.bofh.it> (permalink)
References	<tA4aS-2hp-13@gated-at.bofh.it> <tA90S-5mC-11@gated-at.bofh.it> <tB98u-4Ii-11@gated-at.bofh.it> <tBcJ4-6Ni-15@gated-at.bofh.it> <tEM3E-1q2-5@gated-at.bofh.it>
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> However, the fact is that PHYs having active 1G/s link generate much
> more heat than having 100M/s link independently from network traffic.

Yes, this is true. I got an off-list email suggesting this power
difference is very significant, more so than actually processing
packets.

> All cooling methods impact host only, but "net cooling" impacts remote
> side in addition, which seems to me to be a problem sometimes. Also,
> the moment of link renegotiation blocks rx/tx for upper layers, so the
> user sees a pause when streaming a video for example. However, if a
> system is under a thermal condition, does it really matter?

I don't know the cooling subsystem too well. Can you express a 'cost'
for making a change, as well as the likely result in making the
change. You might want to make the cost high, so it is used as a last
resort if other methods cannot give enough cooling.

       Andrew

Thread

Network cooling device and how to control NIC speed on thermal condition Waldemar Rymarkiewicz <waldemar.rymarkiewicz@gmail.com> - 2017-04-25 10:40 +0200
  Re: Network cooling device and how to control NIC speed on thermal  condition Andrew Lunn <andrew@lunn.ch> - 2017-04-25 15:20 +0200
  Re: Network cooling device and how to control NIC speed on thermal  condition Alan Cox <gnomes@lxorguk.ukuu.org.uk> - 2017-04-25 15:50 +0200
    Re: Network cooling device and how to control NIC speed on thermal condition Waldemar Rymarkiewicz <waldemar.rymarkiewicz@gmail.com> - 2017-04-28 10:10 +0200
      Re: Network cooling device and how to control NIC speed on thermal  condition Andrew Lunn <andrew@lunn.ch> - 2017-04-28 14:00 +0200
        Re: Network cooling device and how to control NIC speed on thermal condition Waldemar Rymarkiewicz <waldemar.rymarkiewicz@gmail.com> - 2017-05-08 10:20 +0200
          Re: Network cooling device and how to control NIC speed on thermal  condition Andrew Lunn <andrew@lunn.ch> - 2017-05-08 16:10 +0200
  Re: Network cooling device and how to control NIC speed on thermal  condition Florian Fainelli <f.fainelli@gmail.com> - 2017-04-25 18:30 +0200

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