Re: [linuxwifi] [RFC] iwlwifi: enable TX AMPDU for some iwldvm

["Grumbach, Emmanuel" <emmanuel.grumbach@intel.com>]

On Tue, 2019-03-12 at 21:38 +0200, Luciano Coelho wrote:
> Hi Kevin,
> 
> Johannes (johill) is also in this list. :)
> 
> If this feature was explicitly disabled, it certainly means that
> something was causing problems with it, so I'd be wary to enable it
> for
> all DVM devices.
> 
> I guess we could enable it by default for devices that work fine, but
> we would have to run it in real life for a lot longer with a lot more
> different APs to be sure it won't cause any problems.
> 
> Emmanuel, do you happen to remember what was the issue, so Kevin
> could
> test that specific scenario with this specific NIC?

long long nights of despair.

We had issues with reclaim path upon BACK. This is of course a firmware
problem...

> 
> Kevin, meanwhile you could add the option to your default module
> configuration so it would be used by default on your machine.
> 
> --
> Cheers,
> Luca.
> 
> 
> On Tue, 2019-03-12 at 11:12 -0600, Kevin Locke wrote:
> > Hi Wireless Developers,
> > 
> > I have a Lenovo ThinkPad T430 (2342-CTO) with an Intel Centrino
> > Ultimate-N 6300 (8086:4238) wireless card.  With the help of
> > Reventlov
> > and johill on #linux-wireless, we discovered that enabling TX
> > AMPDU,
> > by passing module option 11n_disable=8 (IWL_ENABLE_HT_TXAGG) to
> > iwlwifi, increased TCP throughput significantly:
> > 
> > With an ASUS RT-ACRH13 AP and `iperf3 -s` running on a server with
> > a
> > 1Gbps wired connection, `iperf3 -R -c` on the ThinkPad increased
> > from
> > 63.2 to 104 Mbits/sec (using MCS 15 40MHz short GI).  With a
> > Buffalo
> > WZR-600DHP running OpenWRT, `iperf3 -R -c` increased from 63.2 to
> > 76.9.
> > 
> > TX AMPDU was disabled by default for all iwldvm cards in
> > 205e2210daa9
> > because "iwldvm don't handle well TX AMPDU".  However, I have been
> > using this configuration for >2 weeks without any issues or
> > measurable
> > change in ping times to the AP.  Are there any other potential
> > side-effects I can check?
> > 
> > Would it be possible to enable TX AMPDU by default for at least
> > some
> > of these cards?  If so, what additional information would be
> > required?
> > 
> > Thanks for considering,
> > Kevin
> > -------------------------------------
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>