On 08/16/2017 07:11 PM, Dan Williams wrote:
On Wed, 2017-08-16 at 14:31 -0700, David Miller wrote:
From: Dan Williams <dcbw@xxxxxxxxxx>
Date: Wed, 16 Aug 2017 16:22:41 -0500
My biggest suggestion is that perhaps bonding should grow
hysteresis
for link speeds. Since WiFi can change speed every packet, you
probably
don't want the bond characteristics changing every couple seconds
just
in case your WiFi link is jumping around. Ethernet won't bounce
around
that much, so the hysteresis would have no effect there. Or, if
people
are concerned about response time to speed changes on ethernet
(where
you probably do want an instant switch-over) some new flag to
indicate
that certain devices don't have stable speeds over time.
Or just report the average of the range the wireless link can hit,
and
be done with it.
I think you guys are overcomplicating things.
That range can be from 1 to > 800Mb/s. No, it won't usually be all
over that range, but it won't be uncommon to fluctuate by hundreds of
Mb/s. I'm not sure a simple average is really the answer here. Even
doing that would require new knobs to ethtool, since the rate depends
heavily on card capabilities and also what AP you're connected to *at
that moment*. If you roam to another AP, then the max speed can
certainly change.
You'll probably say "aim for the 75% case" or something like that,
which is fine, but then you're depending on your 75% case to be (a)
single AP, (b) never move (eg, only bond wifi + ethernet), (c) little
radio interference. I'm not sure I'd buy that. If I've put words in
your mouth, forgive me.
If you keep ethtool API simple and just return the last (rx-rate + tx-rate) / 2, or the rate averaged
over the last 100 frames or 10 seconds, then the caller can do longer term averaging
as it sees fit. Probably no need for lots of averaging complexity in the kernel.
rate-ctrl for wifi basically doesn't happen until you transmit or receive a
fairly steady stream, so it will fluctuate a lot.
Thanks,
Ben
Dan
--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
