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Re: Packet throughput (and those iperf data rate) with mac80211/ath9k is 20% worse than net80211/madwifi

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On 31/01/17 10:46, Klaus Kinski wrote:
BTW, if I read the sources correctly, than IBSS mode uses the TXQ parameters from ieee80211_set_wmm_default with enable_qos = false which means that qparam.txop = 0, e.g. bursting is disabled. Am I right?
I guess so. But you need to look also at contention window sizes because it make a big impact on throughout with retries and collisions.

Jörg Pommnitz <jpo234@xxxxxxxxxx <mailto:jpo234@xxxxxxxxxx>> schrieb am Di., 31. Jan. 2017 um 10:37 Uhr:

    I'm mostly interested in Ad-Hoc mode, e.g. IBSS.

    Wojciech Dubowik <wojciech.dubowik@xxxxxxxxxxx
    <mailto:wojciech.dubowik@xxxxxxxxxxx>> schrieb am Di., 31. Jan.
    2017 um 10:35 Uhr:

        That's tricky but look at
        http://w1.fi/cgit/hostap/tree/hostapd/hostapd.conf
        <http://w1.fi/cgit/hostap/tree/hostapd/hostapd.conf>

        tx_queue... are for AP and wmm_... for STA (over beacons).

        These should be default parameters. You can also enable CONFIG
        debug flag

        for ath9k and it prints wme parameters when it starts.

        Wojtek


        On 31/01/17 10:18, Klaus Kinski wrote:
        It seems that bursting can be controlled over nl80211 (see ,
        specifically with NL80211_ATTR_WIPHY_TXQ_PARAMS.
        Unfortunately this seems not to be exposed in iw. It's an
        attribute of NL80211_CMD_SET_WIPHY.
        Is there another tool that exposes txq params? If not, has
        anybody thought about exposing it in iw? I might take a stab
        at it...

        Regards
          Joerg

        Wojciech Dubowik <wojciech.dubowik@xxxxxxxxxxx
        <mailto:wojciech.dubowik@xxxxxxxxxxx>> schrieb am Di., 31.
        Jan. 2017 um 08:55 Uhr:

            Madwifi has default best effort queue "tuned" for throughout

            and its parameters are different from mac80211 defaults when

            qos  (WME) is disabled.

            You would have to dump qos settings for both systems before

            comparing them. I guess the easiest way is to make sure QoS

            is enabled and send video type of packets with iperf ...
            -S 0xa0

            Wojtek


            On 30/01/17 20:43, Toke Høiland-Jørgensen wrote:
            > Klaus Kinski <jpo234@xxxxxxxxxx
            <mailto:jpo234@xxxxxxxxxx>> writes:
            >
            >> The captures I used to create the statistics are here:
            >>
            https://drive.google.com/open?id=0ByFGz3ZH6JcYMGp0a05lYzBPNzA
            >>
            >> An obvious difference is, that Madwifi sends 5 packets
            in a row
            >> without waiting for an ACK whereas ath9k/mac80211
            always seems to wait
            >> for an ACK. This seems to point to the "net80211
            aggressive mode
            >> theory" https://wiki.freebsd.org/WifiAggressiveMode
            <https://wiki.freebsd.org/WifiAggressiveMode>, IMHO.
            > I'm not too familiar with that part of the stack, but
            that seems
            > reasonable, yeah. AFAIK the "aggresive mode" is a
            pre-802.11n feature,
            > though, which is why you won't see that in ath9k. In
            802.11n this kind
            > of bursting was replaced by aggregation, which you're
            not getting any of
            > since you're running in 802.11a mode, obviously.
            >
            > The lack of bursting will translate to slightly lower
            throughput, which
            > will be why you see fewer packets transmitted by ath9k.
            Of course, if
            > your receiver supported aggregation, the numbers would
            look dramatically
            > better in ath9k's favour... ;)
            >
            > -Toke





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