Date: Mon, 26 Sep 2011 20:37:24 +0530
From: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
To: Felix Fietkau <nbd@openwrt.org>
CC: <johannes@sipsolutions.net>, <linville@tuxdriver.com>,
	<linux-wireless@vger.kernel.org>
Subject: Re: [RFC v3] mac80211: Send nullfunc frames at lower rate
Message-ID: <20110926150722.GA9947@vmraj-lnx.users.atheros.com> (sfid-20110926_170744_618740_B66F8DEF)
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 <4E807F71.1010809@openwrt.org>
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On Mon, Sep 26, 2011 at 07:34:41AM -0600, Felix Fietkau wrote:
> On 2011-09-26 6:23 AM, Rajkumar Manoharan wrote:
> >Recently mac80211 was changed to use nullfunc instead of probe
> >request for connection monitoring for tx ack status reporting
> >hardwares. These nullfunc data frames are being sent at higer
> >rates and also as aggregated ones. This could probably delays
> >the nullfunc ack so the connection is more frequently getting
> >disconnected as max retries are reached. In order to improve
> >the connectivity send the nullfunc at lower rate.
> I don't think nullfunc frames should be sent at the lowest rate. If
> they fail frequently, then the rate control module is doing
> something crappy and should be fixed. So far I haven't seen any
> nullfunc reliablity issues with minstrel_ht.
> Also, as far as I know, mac80211 sends non-QoS nullfunc frames, so
> they cannot get aggregated either.
>
Whatever you mentioned is completely fine, if nullfunc is not used for
monitoring purpose. Otherwise the nullfunc can be aggregated and on worst
case it will be retried to max and BAR will be exchange. By the time
the connection was terminated. As we are using nulldata for controlling
the connection, IMHO it is not wrong to send it at min rate. So we can
avoid unnecessary disconnections.

--
Rajkumar