From: Stanislaw Gruszka <sgruszka@redhat.com>
To: linux-wireless@vger.kernel.org
Cc: "Tomislav Požega" <pozega.tomislav@gmail.com>,
"Daniel Golle" <daniel@makrotopia.org>,
"Felix Fietkau" <nbd@nbd.name>, "Mathias Kresin" <dev@kresin.me>
Subject: Re: [RFC/RFT] rt2x00: do not set IEEE80211_TX_STAT_AMPDU_NO_BACK on tx status
Date: Fri, 12 Jul 2019 12:25:10 +0200 [thread overview]
Message-ID: <20190712102510.GA17258@redhat.com> (raw)
In-Reply-To: <20190704110652.3955-1-sgruszka@redhat.com>
On Thu, Jul 04, 2019 at 01:06:52PM +0200, Stanislaw Gruszka wrote:
> According to documentation IEEE80211_TX_STAT_AMPDU_NO_BACK is suppose
> to be used when we do not recive BA (BlockAck). However on rt2x00 we
> use it when remote station fail to decode one or more subframes within
> AMPDU (some bits are not set in BlockAck bitmap). Setting the flag result
> in sent of BAR (BlockAck Request) frame and this might result of abuse
> of BA session, since remote station can sent BA with incorrect
> sequence numbers after receiving BAR. This problem is visible especially
> when connecting two rt2800 devices.
>
> Previously I observed some performance benefits when using the flag
> when connecting with iwlwifi devices. But currently possibly due
> to reacent changes in rt2x00 removing the flag has no effect on
> those test cases.
>
> So remove the IEEE80211_TX_STAT_AMPDU_NO_BACK.
>
> Perhaps we should send BAR exlicitly on BA session start/stop
> and when remote STA went to PowerSave mode (for AP) like mt76 does.
> But I do not understand for what this is needed.
This commit
https://github.com/openwrt/mt76/commit/3e447e7797d64dbf4dc1dd5553d08be0d8150d7e
explained that sending BAR on stop aggregation is workaround for
buggy clients. I can implement that on rt2x00. But I will skip
sending BAR on remote station PS wakeup, since we do not implement
all PS related code in rt2x00.
Stanislaw
prev parent reply other threads:[~2019-07-12 10:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-04 11:06 [RFC/RFT] rt2x00: do not set IEEE80211_TX_STAT_AMPDU_NO_BACK on tx status Stanislaw Gruszka
2019-07-12 10:25 ` Stanislaw Gruszka [this message]
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