The symptom: sometimes 11n (and non-11n) throughput is great.
Sometimes it isn't. Much teeth gnashing occured, and much kernel
bisecting happened, until someone figured out it was the order
of which things were rebooted, not the kernel versions.
(Which was great news to me, it meant that I hadn't broken if_ath.)
What we found was that sometimes the WME parameters for the best-effort
queue had a burst window ("txop") in which the station would be allowed
to TX as many packets as it could fit inside that particular burst
window. This improved throughput.
After initially thinking it was a bug - the WME parameters for the
best-effort queue -should- have a txop of 0, Bernard and I discovered
"aggressive mode" in net80211 - where the WME BE queue parameters
are changed if there's not a lot of high priority traffic going on.
The WME parameters announced in the association response and beacon
frames just "change" based on what the current traffic levels are.
So in fact yes, the STA was acutally supposed to be doing this higher
throughput stuff as it's just meant to be configuring things based on
the WME parameters - but it wasn't.
What was eventually happening was this:
* at startup, the wme qosinfo count field would be 0;
* it'd be parsed in ieee80211_parse_wmeparams();
* and it would be bumped (to say 10);
* .. and the WME queue parameters would be correctly parsed and set.
But then, when you restarted the assocation (eg hostap goes away and
comes back with the same qosinfo count field of 10, or if you
destroy the sta VIF and re-create it), the WME qosinfo count field -
which is associated not to the VIF, but to the main interface -
wouldn't be cleared, so the queue default parameters would be used
(which include no burst setting for the BE queue) and would remain
that way until the hostap qosinfo count field changed, or the STA
was actually rebooted.
This fix simply cleares the wme capability field (which has the count
field) to 0, forcing it to be reset by the next received beacon.
Thanks go to Milu for finding it and helping me track down what was
going on, and Bernard Schmidt for working through the net80211 and
WME specific magic.
uses of ic_curchan occur. Due to the nature of a scan, switching
channels constantly and all this happening without any kind of locks
held, it might happen that ic_curchan points to nowhere leading to
panics. Fix this by not allowing frame injections while in SCAN state.
Tested by: Paul B. Mahol <onemda at gmail.com>
If multiple networks are available the max bandwidth is one
condition used for selecting the "best" BSS. To achieve that
we should consider all parameters which affect the max RX rate.
This includes 20/40MHz, SGI and the of course the MCS set.
If the TX MCS parameters are available we should use those,
because an AP announcing support for receiving frames at 450Mbps
might only be able to transmit at 150Mbps (1T3R). I haven't seen
devices with support for transmitting at higher rates then
receiving, so prefering TX over RX information should be safe.
While here, remove the hardcoded assumption that MCS15 is the max
possible MCS rate, use MCS31 instead which really is the highest
rate (according to the 802.11n std). Also, fix a mismatch of an
40MHz/SGI check.
Contrary to the rateset information in legacy frames the MCS Set
field also contains TX capability information in cases where the
number of available TX and RX spartial streams differ. Because a
rateset doesn't contain that information we have to pull the
those directly from the hardware capabilities.
Get rid of the assumption that every device is capable of 40MHz,
SGI and 2 spartial streams. Instead of printing, in the worst case,
8 times 76 MCS rates, print logically connect ranges and the
support RX/TX streams.
A device without 40MHz and SGI support looks like:
ath0: 2T2R
ath0: 11na MCS 20Mhz
ath0: MCS 0-7: 6.5Mbps - 65Mbps
ath0: MCS 8-15: 13Mbps - 130Mbps
ath0: 11ng MCS 20Mhz
ath0: MCS 0-7: 6.5Mbps - 65Mbps
ath0: MCS 8-15: 13Mbps - 130Mbps
Initialize ic_rxstream/ic_txstream with 2, for compatibility reasons.
Introduce 4 new HTC flags, which are used in addition to ic_rxstream
and ic_txstream to compute the hc_mcsset content and also for initializing
ni_htrates. The number of spatial streams is enough to determine support
for MCS0-31 but not for MCS32-76 as well as some TX parameters in the
hc_mcsset field.
adjust the IEEE80211_HTRATE_MAXSIZE constant, only MCS0 - 76 are valid
the other bits in the mcsset IE (77 - 127) are either reserved or used
for TX parameters.
clean up parts of the *_recv_mgmt() functions.
- make sure appropriate counters are bumped and debug messages are printed
- order the unhandled subtypes by value and add a few missing ones
- fix some whitespace nits
- remove duplicate code in adhoc_recv_mgmt()
- remove a useless comment, probably left in while c&p
The current code transmits management and multicast frames at MCS 0.
What it should do is check whether the negotiated basic set is zero (and
the MCS set is not) before making this decision.
For now, simply default to the lowest negotiated rate, rather than
MCS 0. This fixes the behaviour with at least the DLINK DIR-825, which
ACKs but silently ignores block-ack (BA) response frames.
if a scan is running, report if a scan has been started. The return value
itself is not (yet) used anywhere in the tree and it is also not exported
to userspace.
MFC after: 1 month
the element's data length, frm[2] is the first byte of the element's data.
Submitted by: Monthadar Al Jaberi <monthadar at gmail.com>
MFC after: 1 week
This fixes hostap mode for at least ral(4) and run(4), because there is
no sufficient call into drivers which could be used initialize the node
related ratectl variables.
MFC after: 3 days
beacon or probe-response frames. Fix the condition by checking for the
the array's content instead of the always existing array itself.
Reviewed by: rpaulo, stefanf
MFC after: 3 days
its internal data. This has been used to bypass missing calls in drivers
which do not use the ratectl framework correctly. Issue is, not all algos
use that variable, or even have internal data, therefore valid calls are
not done. Fix this by removing the checks, all driver issues should be
resolved.
MFC after: 1 week
the currently selected rate. The calculations of course need a valid
rate. To make that possible before any call to node_rate() is done,
initialize ni_txrate on none_node_init() calls.
MFC after: 1 week
the IEEE80211_C_RATECTL flag set, default to NONE for all drivers. Only if
a driver calls ieee80211_ratectl_init() check if the NONE algo is still
selected and try to use AMRR in that case. Drivers are still free to use
any other algo by calling ieee80211_ratectl_set() prior to the
ieee80211_ratectl_init() call.
After this change it is now safe to assume that a ratectl algo is always
available and selected, which renders the IEEE80211_C_RATECTL flag pretty
much useless. Therefore revert r211314 and 211546.
Reviewed by: rpaulo
MFC after: 2 weeks
This can happen if the algos are built as modules but are not loaded. If
the selected ratectl algo is not available, try to load it (The load
module functions does nothing currently). Add a dummy ratectl algo which
always selects the first available rate. Use that one if the desired algo
is not available.
MFC after: 1 week
802.11 duplicate detection. Upon looking at the standard, we discover
that 802.11-2007 says:
"A receiving QoS STA is also required to keep only the most recent
cache entry per<Address 2, TID, sequence-number> triple, storing only
the most recently received fragment number for that triple. A receiving
STA may omit tuples obtained from broadcast/multicast or ATIM frames
from the cache."
To fix this, we just disable duplicate detection for multicast/broadcast
frames.
Reviewed by: sam
MFC after: 4 weeks
Obtained from: DragonFly
queue length. The default value for this parameter is 50, which is
quite low for many of today's uses and the only way to modify this
parameter right now is to edit if_var.h file. Also add read-only
sysctl with the same name, so that it's possible to retrieve the
current value.
MFC after: 1 month
ratectl_node_init() functions and since ni_rtctls was already
malloc'ed() we will panic. Fix this by using the already malloc'ed
pointer.
Found by: bschmidt
Reviewed by: bschmidt
* WPA-None requires ap_scan=2:
The major difference between ap_scan=1 (default) and 2 is, that no
IEEE80211_IOC_SCAN* ioctls/functions are called, though, there is a
dependency on those. For example the call to wpa_driver_bsd_scan()
sets the interface UP, this never happens, therefore the interface
must be marked up in wpa_driver_bsd_associate(). IEEE80211_IOC_SSID
also is not called, which means that the SSID has not been set prior
to the IEEE80211_MLME_ASSOC call.
* WPA-None has no support for sequence number updates, it doesn't make
sense to check for replay violations..
* I had some crashes right after the switch to RUN state, issue is
that sc->sc_lastrs was not yet defined.
Approved by: rpaulo (mentor)
MFC after: 3 weeks
