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Message-ID: <1580325769.26012.54.camel@gmail.com>
Subject: Re: Strange performance issue when using two devices at once
From:   Marlon Smith <marlon.smith10@gmail.com>
To:     Ben Greear <greearb@candelatech.com>,
        linux-wireless@vger.kernel.org
Date:   Wed, 29 Jan 2020 14:22:49 -0500
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         <2e80a485-892d-3b29-19c7-38a9caa14f4b@candelatech.com>
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On Wed, 2020-01-29 at 10:42 -0800, Ben Greear wrote:
> On 1/29/20 10:39 AM, Marlon Smith wrote:
> > 
> > Hi everyone,
> > 
> > I have two RT5370 devices connected to the same access point. Both
> > devices are very slow, but the instant I disconnect one device, the
> > other speeds up by a factor of 10.
> Out of curiosity, are both of the RT5370 used on the same client
> device?
> > Did you check that they have unique MAC addresses?
> > Thanks,
> Ben
> > > 
> > 
> > The really strange part is that one device will perform slowly even
> > if
> > the other device is basically idle! I've confirmed this with a
> > packet
> > sniffer.
> > 
> > I've been trying to do some debugging, and I've found that when
> > both
> > devices are connected to the access point, they report a large
> > number
> > of duplicate frames. I added some debug output
> > in ieee80211_rx_h_check_dup() to confirm that this only happens
> > while
> > both devices are connected. The packet sniffer also shows a large
> > number of retries while this is occurring.
> > 
> > Using backports 5.3-rc4 for this, but also tested on 4.14-rc2.
> > 
> > I did post about this previously on this mailing list (RT5370
> > performance issues), but I thought I'd post again with this new
> > information and more descriptive title. I'm a little bit stuck on
> > this
> > for a while now, so any ideas are much appreciated.
> > 
> > Thanks!
> > 
> > Marlon
> > 

They are on separate devices, although the mac addresses are close.
70:F1:1C:2E:AF:B4 and
70:F1:1C:2E:AF:B6.

However, I have a third device 70:F1:1C:2E:AF:BB which performs well
and does not affect the performance of the other two.