Wow, 160-180 Mb/s. That's great :-) No, it's HT40 but my AP is not very good, it sends to me only A-MSDUs but no A-MPDUs (don't know why, i guess because it's cheap), and there are many WLANs in my neighbourhood in 2.4GHZ and no WLANs in 5GHZ but unfortunately i have an 2GHZ only AP. Furthermore, i don't have any documentation about the Ralink chip i have, only Linux source code from Ralink which i study in order to learn how the device works :-) But it's OK, i'm making progress.
For which devices did you develop 802.11n drivers ? And what AP did you use in your tests ? Alex. On Sun, Feb 14, 2010 at 8:57 PM, Sam Leffler <s...@errno.com> wrote: > That's great to hear. I take it this is HT20? I believe you can get 40-60 > Mb/s @ MCS15 w/o AMPDU and 80-100 Mb/s w/ AMPDU. In HT40 I've gotten > 160-180 Mb/s for TCP netperf (5GHz) and 220+ Mb/s for unidirectional streams > (netperf -t UDP_STREAM). Note that once you get to these higher rates > things like TCP window sizes become important and doing things like TSO in > s/w can give noticeable speed boosts. > > Sam > > Alexander Egorenkov wrote: > >> Hi, >> >> thanks for your help, I implemented A-MPDU Tx in my Ralink driver now and >> it works very good. >> I have average Tx rate about 4.5~5 MBytes/s now :-) The Ralink chip that i >> have implements the frame queue in hardware so i had only to assign sequence >> numbers, set BA window size and MPDU density and it worked, lucky me :-) >> >> Alex. >> >> On Sun, Jan 31, 2010 at 8:20 PM, Sam Leffler <s...@errno.com <mailto: >> s...@errno.com>> wrote: >> >> Alexander Egorenkov wrote: >> >> Why doesn't 802.11 stack assign sequence numbers to A-MPDU frames ? >> >> >> Because if net80211 does the assignment it may be wrong. As the >> comment says, if tx aggregation causes frames to be q'd above the >> h/w then by the time they are sent OTA the pre-assigned seq# may be >> invalidated by other frames going out ahead of it. >> >> >> When sequence numbers are not assigned to A-MPDU frames, then BA >> doesn't work with my AP. >> I tried to assign sequence numbers to A-MPDU frames in my device >> driver and then BAs worked >> with my AP. >> >> >> That is what the comment says to do. >> >> >> And what is meant by aggregation queue ? Where is that queue anf >> how do i use it ? >> >> >> The aggregation q is the mechanism used to hold frames waiting for >> additional frames to aggregated into an A-MSDU/A-MPDU. The queue is >> typically wherever the aggregation work is done. Some devices do >> this in h/w, others require the host handle this. When done in the >> host it can be done in the driver or above. The intent has always >> been to have net80211 implement tx aggregation that a driver can >> fallback on but I never did the work. All the 11n drivers I've done >> have either handled tx aggregation in h/w or in the driver. >> >> >> Thanks. >> >> >> On Sun, Jan 31, 2010 at 4:43 AM, Sam Leffler <s...@errno.com >> <mailto:s...@errno.com> <mailto:s...@errno.com >> >> <mailto:s...@errno.com>>> wrote: >> >> Alexander Egorenkov wrote: >> >> Sorry, i posted the wrong comment. >> Here is the comment which i don't understand: >> >> /* >> * NB: don't assign a sequence # to potential >> * aggregates; we expect this happens at the >> * point the frame comes off any aggregation q >> * as otherwise we may introduce holes in the >> * BA sequence space and/or make window accouting >> * more difficult. >> * >> * XXX may want to control this with a driver >> * capability; this may also change when we pull >> * aggregation up into net80211 >> */ >> >> Thanks. >> >> >> What is unclear? >> >> Sam >> >> >> >> On Wed, Jan 27, 2010 at 8:04 PM, Alexander Egorenkov < >> egore...@googlemail.com <mailto:egore...@googlemail.com> >> <mailto:egore...@googlemail.com >> >> <mailto:egore...@googlemail.com>>> wrote: >> >> Hi, >> >> i'm implementing a device driver for a 802.11n NIC under >> FreeBSD 8 >> und experimented with A-MPDU transmission. I looked into >> net80211 code >> and there is some code which implements this feature >> but it >> worked not very >> well for me. >> I noticed e.g. that sequence numbers are not assigned to >> A-MPDU frames >> and found this comment in file ieee80211_output.c : >> >> >> /* >> * Check if A-MPDU tx aggregation is setup or >> if we >> * should try to enable it. The sta must be >> associated >> * with HT and A-MPDU enabled for use. When >> the policy >> * routine decides we should enable A-MPDU we >> issue an >> * ADDBA request and wait for a reply. The >> frame being >> * encapsulated will go out w/o using A-MPDU, >> or possibly >> * it might be collected by the driver and >> held/retransmit. >> * The default ic_ampdu_enable routine handles >> staggering >> * ADDBA requests in case the receiver NAK's >> us or we are >> * otherwise unable to establish a BA stream. >> */ >> >> Can somebody elaborate this description to me please. >> >> Thanks. >> >> ALex. >> >> >> _______________________________________________ >> freebsd-net@freebsd.org <mailto:freebsd-net@freebsd.org> >> <mailto:freebsd-net@freebsd.org >> <mailto:freebsd-net@freebsd.org>> mailing >> >> list >> http://lists.freebsd.org/mailman/listinfo/freebsd-net >> To unsubscribe, send any mail to >> "freebsd-net-unsubscr...@freebsd.org >> <mailto:freebsd-net-unsubscr...@freebsd.org> >> <mailto:freebsd-net-unsubscr...@freebsd.org >> <mailto:freebsd-net-unsubscr...@freebsd.org>>" >> >> >> >> >> >> >> > _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
