Re: [Make-wifi-fast] Upcoming WiFi standard to set per-flow DSCP values?

[Bob McMahon <bob.mcmahon@broadcom.com>]

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hmm, curious about the side effects.

I perceive the multiple queues with static EDCAs as a poor man's version of
adaptive EDCAs where every transmit could have the EDCAs defined via a
delayed binding just prior to transmit arbitration. Also, things like push
in first out (PIFO) hw queues <http://web.mit.edu/pifo/> seem interesting
allowing a TCP 3WHS and the first few packets (mouse flow) to jump the
line, similar to an express lane at a grocery store.

Bob

On Sun, Jan 9, 2022 at 6:41 PM Dave Taht <dave.taht@gmail.com> wrote:

> I've tried to describe the side effects of using all 4 of these queues
> in nearly every talk. I'd really like it if the AP drivers just better
> multiplexed best effort traffic and modified the values in the beacon.
>
> I do see more value in pushing out queue selection to the clients, if
> used sparingly.
>
> On Wed, Jan 5, 2022 at 9:12 AM Aaron Wood <woody77@gmail.com> wrote:
> >
> > I'm guessing that schemes like this are mostly aimed-at, or
> developed-by, at the enterprise wifi market, where you have mixed uses
> being run on the same AP (much like running separate vlans on the same
> wired network), to mix both "infrastructure" uses which have priority, and
> "guests" networks which have less priority.  When I was in that part of the
> industry, I was seeing this a lot, the general attempt to move the QoS and
> vlans from wired networks into WLAN and WAN links.
> >
> > On Wed, Jan 5, 2022 at 4:28 AM Sebastian Moeller <moeller0@gmx.de>
> wrote:
> >>
> >> Hi Toke, hi Jon,
> >>
> >> here is a corrected version of what I sent to another list (I
> accidentally converted the VA bit-pattern with my calculator set to base8
> so decimal 54 and Range7 instead of the correct decimal 44 and Range6,
> which does not change much for the AC mapping as both range6 and 7 map to
> AC_VO):
> >>
> >> >> hostapd: add wmm qos map set by default
> >> >> author       Felix Fietkau <nbd@nbd.name>
> >> >> Wed, 3 Nov 2021 22:40:53 +0100 (22:40 +0100)
> >> >> committer    Felix Fietkau <nbd@nbd.name>
> >> >> Wed, 3 Nov 2021 22:47:55 +0100 (22:47 +0100)
> >> >> commit       a5e3def1822431ef6436cb493df77006dbacafd6
> >> >> tree f4494efd6e08a872524eedb5081564a6f5ece20c        tree | snapshot
> >> >> parent       b14f0628499142a718a68be7d1a7243f7f51ef0a        commit
> | diff
> >> >> hostapd: add wmm qos map set by default
> >> >>
> >> >> This implements the mapping recommendations from RFC8325, with an
> >> >> update from RFC8622. This ensures that DSCP marked packets are
> properly
> >> >> sorted into WMM classes.
> >> >> The map can be disabled by setting iw_qos_map_set to something
> invalid
> >> >> like 'none'
> >> >>
> >> >> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> >> >
> >> > Which introduces the following new RFC8325 inspired DSCP to AC
> mappings:
> >> > +       set_default iw_qos_map_set
> 0,0,2,16,1,1,255,255,18,22,24,38,40,40,44,46,48,56
> >> >
> >> > Which translates into the following mappings (according to the
> hostapd rules below*):
> >> >
> >> > unraveling this gets us to (0 is coded as DSCP Exception, the rest as
> DSCP ranges):
> >> >
> >> > UP    DSCP    AC      PHBs(decDSCP)
> >> > Ex0   BE      BE(0)   BE/CS0(0)
> >> > Range0        2-16    BE      CS1(8)**, AF11(10), AF12(12), AF13(14),
> CS2(16)
> >> > Range1        1-1     BK      LE(1)
> >> > Range2        -
> >> > Range3        18-22   BE      AF21(18), AF22(20), AF23(22)
> >> > Range4        24-38   VI      CS3(24), AF31(26), AF32(28), AF33(30),
> CS4(32), AF41(34), AF42(36), AF43(38)
> >> > Range5        40-40   VI      CS5(40)
> >> > Range6        44-46   VO      VA(44), EF(46)
> >> > Range7        48-56   VO      CS6(48), CS7(56)
> >>
> >> The kernel's default mappings, as far as
> https://wireless.wiki.kernel.org/en/developers/documentation/mac80211/queues
> states, seem driven by the top 3 bits of the DSCP field:
> >> RFC8325 also has a section about the default mappings
> >>
> >> UP      DSCP    AC      PHBs(decDSCP)
> >> Range0  0-7     BE      CS0(0)
> >> Range1  8-15    BK      CS1(8), AF11(10), AF12(12), AF13(14)
> >> Range2  16-23   BK      CS2(16), AF21(18), AF22(20), AF23(22)
> >> Range3  24-31   BE      CS3(24), AF31(26), AF32(28), AF33(30)
> >> Range4  32-39   VI      CS4(32), AF41(34), AF42(36), AF43(38)
> >> Range5  40-47   VI      CS5(40), VA(44), EF(46)
> >> Range6  48-55   VO      CS6(48)
> >> Range7  56-63   VO      CS7(56)
> >>
> >>
> >> IMHO RFC8325 and the whole WMM scheme clearly lacks data showing that
> is actually delivers on its promises. RFC8325 specifically seems obsessed
> in changing mappings such that PHBs align with the 4 WMM queues, instead of
> interpreting the fact that the apparent mismatch between what the IETF
> thinks about specific PHBs/DSCPs and how they are treated for most users,
> as clear sign, that reality does not care... (probably mostly driven by the
> elephant in the room, of DSCPs not being end-to-end).
> >>
> >> I agree with Toke that allowing APs to steer specific DSCP use by
> applications seems taking an proven non-working idea to the extreme... (APs
> can already instruct stations on which DSCPs to map to which AC (see
> Felix's patch), which is not used that much, no idea why anybody thinks
> that allowing APs even more disruptive changes to end-point behavior is
> going to work any better).
> >>
> >> Regards
> >>         Sebastian
> >>
> >> P.S.: IMHO the biggest change might be the up-prioritisation of EF from
> AC_VI to AC_VO, and I am not sure that is a good idea.
> >>
> >>
> >>
> >> > On Jan 5, 2022, at 13:02, Toke Høiland-Jørgensen via Make-wifi-fast <
> make-wifi-fast@lists.bufferbloat.net> wrote:
> >> >
> >> > Jon Pike <jonpike54@gmail.com> writes:
> >> >
> >> >> Heh...  So each and everyone in the stadium can have ALL their data
> >> >> prioritized above everybody else's!  For a more Egalitarian world!
> >> >>
> >> >> Sigh...   Meanwhile, back in reality...
> >> >>
> >> >> An aside, is that commit in git a significant improvement on the
> mappings,
> >> >> or just some minor tweaks?
> >> >
> >> > I *think* they are just minor tweaks, but I don't actually recall the
> >> > exact mapping that's the kernel default...
> >> >
> >> > -Toke
> >> > _______________________________________________
> >> > Make-wifi-fast mailing list
> >> > Make-wifi-fast@lists.bufferbloat.net
> >> > https://lists.bufferbloat.net/listinfo/make-wifi-fast
> >>
> >> _______________________________________________
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> >
> > _______________________________________________
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>
>
>
> --
> I tried to build a better future, a few times:
> https://wayforward.archive.org/?site=https%3A%2F%2Fwww.icei.org
>
> Dave Täht CEO, TekLibre, LLC
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