Subject: Re: [PATCH v2 2/2] mac80211: minstrel_ht: set A-MSDU tx limits based
 on selected max_prob_rate
To: Johannes Berg <johannes@sipsolutions.net>,
	linux-wireless@vger.kernel.org
References: <1456306140-78485-1-git-send-email-nbd@openwrt.org>
 <1456306140-78485-2-git-send-email-nbd@openwrt.org>
 <1457016949.2044.12.camel@sipsolutions.net>
Cc: egrumbach@gmail.com
From: Felix Fietkau <nbd@openwrt.org>
Message-ID: <56D85246.8070306@openwrt.org> (sfid-20160303_160355_936410_D5CA588F)
Date: Thu, 3 Mar 2016 16:03:34 +0100
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In-Reply-To: <1457016949.2044.12.camel@sipsolutions.net>
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Sender: linux-wireless-owner@vger.kernel.org

On 2016-03-03 15:55, Johannes Berg wrote:
> On Wed, 2016-02-24 at 10:29 +0100, Felix Fietkau wrote:
> 
>> +	/*
>> +	 * If the rate is slower than single-stream MCS4, limit A-MSDU to usual
>> +	 * data packet size
>> +	 */
>> +	if (g->duration[rate] > MCS_DURATION(1, 0, 104))
>> +		return 1500;
>> +
>> +	/*
>> +	 * If the rate is slower than single-stream MCS7, limit A-MSDU to twice
>> +	 * the usual data packet size
>> +	 */
>> +	if (g->duration[rate] > MCS_DURATION(1, 0, 260))
>> +		return 3000;
> 
> This isn't *quite* right, since you have to take an 802.11 header (vs.
> an ethernet header) into account, I think?
It's only a rough approximation anyway to prevent very large A-MSDUs
from being created with low rates.

- Felix