Commit Graph

93 Commits

Author SHA1 Message Date
Krishna Chaitanya
a3ebb4e1b7 mac80211: minstrel_ht: handle peers in dynamic SMPS
In case of Dynamic SMPS enable RTS/CTS for all rates.

Signed-off-by: Chaitanya T K <chaitanya.mgit@gmail.com>
[change comment]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2015-07-17 15:38:20 +02:00
Johannes Berg
30686bf7f5 mac80211: convert HW flags to unsigned long bitmap
As we're running out of hardware capability flags pretty quickly,
convert them to use the regular test_bit() style unsigned long
bitmaps.

This introduces a number of helper functions/macros to set and to
test the bits, along with new debugfs code.

The occurrences of an explicit __clear_bit() are intentional, the
drivers were never supposed to change their supported bits on the
fly. We should investigate changing this to be a per-frame flag.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2015-06-10 16:05:36 +02:00
Thomas Huehn
50e55a8ea7 mac80211: add max lossless throughput per rate
This patch adds the new statistic "maximum possible lossless
throughput" to Minstrels and Minstrel-HTs rc_stats (in debugfs). This
enables comprehensive comparison between current per-rate throughput
and max. achievable per-rate throughput.

Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
Acked-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2015-04-01 20:44:32 +02:00
Thomas Huehn
6a27b2c40b mac80211: restructure per-rate throughput calculation into function
This patch moves Minstrels and Minstrel-HTs per-rate throughput
calculation (EWMA(thr)) into a dedicated function to be called.
Therefore the variable "unsigned int cur_tp" within struct
"minstrel_rate_stats" becomes obsolete.  and is removed to free
up its space.

Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
Acked-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2015-04-01 20:44:32 +02:00
Thomas Huehn
9134073bc6 mac80211: improve Minstrel variable & function naming
This patch ensures a consistent usage of variable names for type
"minstrel_rate_stats" to be used as "mrs" and from type minstrel_rate
as "mr" across both Minstrel & Minstrel-HT. In addition some
variable and function names got changed to more meaningful ones.

Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
Acked-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2015-04-01 20:44:31 +02:00
Thomas Huehn
f62838bcc5 mac80211: unify Minstrel & Minstrel-HTs calculation of rate statistics
This patch unifies the calculation of Minstrels and Minstrel-HTs
per-rate statistic. The new common function minstrel_calc_rate_stats()
is called when a statistic update is performed.

Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
Acked-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2015-04-01 20:44:31 +02:00
Felix Fietkau
d66c258278 mac80211: minstrel_ht: fix rounding issue in MCS duration calculation
On very high MCS bitrates, the calculated duration of rates that are
next to each other can be very imprecise, due to the small packet size
used as reference (1200 bytes).
This is most visible in VHT80 nss=2 MCS8/9, for which minstrel shows the
same throughput when the probability is also the same. This leads to a
bad rate selection for such rates.

Fix this issue by introducing an average A-MPDU size factor into the
calculation.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2015-03-17 11:03:30 +01:00
John W. Linville
81c412600f Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless 2014-12-08 13:58:58 -05:00
Felix Fietkau
63558a650a mac80211: minstrel_ht: switch to .tx_status_noskb
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-11-28 15:01:50 +01:00
Felix Fietkau
95943425c0 mac80211: minstrel_ht: move aggregation check to .get_rate()
Preparation for adding a no-skb tx status path

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-11-28 15:01:50 +01:00
Felix Fietkau
75769c80e3 mac80211: minstrel_ht: add a small optimization to minstrel_aggr_check
Check the queue mapping earlier, skb->queue_mapping is more likely than
skb->data to still be in d-cache.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-11-19 19:31:07 +01:00
Felix Fietkau
280ba51d60 mac80211: minstrel_ht: fix a crash in rate sorting
The commit 5935839ad7
"mac80211: improve minstrel_ht rate sorting by throughput & probability"

introduced a crash on rate sorting that occurs when the rate added to
the sorting array is faster than all the previous rates. Due to an
off-by-one error, it reads the rate index from tp_list[-1], which
contains uninitialized stack garbage, and then uses the resulting index
for accessing the group rate stats, leading to a crash if the garbage
value is big enough.

Cc: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
Reported-by: Jouni Malinen <j@w1.fi>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-11-18 22:39:16 +01:00
Karl Beldan
9ffe904405 mac80211: minstrel_ht: do not always skip ht rates vht_only is true
When CONFIG_MAC80211_RC_MINSTREL_VHT is set, the module param
minstrel_vht_only tells minstrel_ht whether to allow the mix of ht rates
with vht rates.
ATM, minstrel_ht skips ht rates when minstrel_vht_only is true, but it does
that even if vht is not supported, which makes the sta rates fallback to
legacy as no ht rate gets enabled.

Fixes: 9208247d74 ("mac80211: minstrel_ht: add basic support for VHT rates <= 3SS@80MHz")
Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-10-27 08:48:35 +01:00
Karl Beldan
9208247d74 mac80211: minstrel_ht: add basic support for VHT rates <= 3SS@80MHz
When the new CONFIG_MAC80211_RC_MINSTREL_VHT is not set (default 'N'),
there is no behavioral change including in sampling and MCS_GROUP_RATES
remains 8.
Otherwise MCS_GROUP_RATES is 10, and a module parameter *vht_only*
(default 'true'), restricts the rates selection to VHT when VHT is
supported.

Regarding the debugfs stats buffer:
It is explicitly increased from 8k to 32k to fit every rates incl. when
both HT and VHT rates are enabled, as for the format, before:
type           rate     tpt eprob *prob ret  *ok(*cum)        ok(      cum)
HT20/LGI ABCDP MCS0     0.0   0.0   0.0   1    0(   0)         0(        0)
after:
 type           rate      tpt eprob *prob ret  *ok(*cum)        ok(      cum)
 HT20/LGI ABCDP MCS0      0.0   0.0   0.0   1    0(   0)         0(        0)
VHT40/LGI       MCS5/2    0.0   0.0   0.0   0    0(   0)         0(        0)

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Cc: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-10-21 13:25:26 +02:00
Karl Beldan
3ec373c421 mac80211: minstrel_ht: include type (cck/ht) in rates flag
ATM, we grep cck rates idx with idx / MCS_GROUP_RATES ==
MINSTREL_CCK_GROUP.
Matching neither-cck-non-ht rates could be done by replacing '==' with
'>', however it would be less versatile or explicit.
This will allow to match VHT rates with IEEE80211_TX_RC_VHT_MCS.

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Cc: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-10-20 21:39:35 +02:00
Karl Beldan
8a0ee4fe19 mac80211: minstrel_ht: macros adjustments for future VHT_GROUPs
No functional change.

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Cc: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-10-20 21:39:35 +02:00
Karl Beldan
d4d141cae8 mac80211: minstrel_ht: Increase the range of handled rate indexes
Since 5935839ad7 ("mac80211: improve minstrel_ht rate sorting by
throughput & probability"), the rate indexes are manipulated via u8's
and hence allow for a maximum of 256 mcs_group entries in
minstrel_mcs_groups.

ATM, minstrel_ht advertizes support up to 3HTSS@40MHz, consuming:
8(MCS_GROUP_RATES) * (3(SS)*2(GI)*2(BW)+1(CCK)), i.e. 104 entries.

Support for 3VHTSS@80MHz will require:
10(MCS_GROUP_RATES) * (3(SS)*2(GI)*2(BW)+1(CCK)) +
10(MCS_GROUP_RATES) * (3(SS)*2(GI)*3(BW)), i.e. 130 + 180 entries.

This change moves from u8s to u16s where necessary.

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Cc: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-10-20 21:39:35 +02:00
Karl Beldan
cc61d8df0a mac80211: minstrel_ht: fix MCS_GROUP_RATES usage
Commit 5935839ad7 ("mac80211: improve minstrel_ht rate sorting by
throughput & probability") replaced the constant 8 with MCS_GROUP_RATES
when getting the number of streams of an HT MCS. See commit 7a5e3fa2c8
("mac80211: minstrel_ht: replace some occurences of MCS_GROUP_RATES").

Fixes: 5935839ad7 ("mac80211: improve minstrel_ht rate sorting by throughput & probability")
Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-10-09 10:51:19 +02:00
Thomas Huehn
5935839ad7 mac80211: improve minstrel_ht rate sorting by throughput & probability
This patch improves the way minstrel_ht sorts rates according to throughput
and success probability. 3 FOR-loops across the entire rate and mcs group set
in function minstrel_ht_update_stats() which where used to determine the
fastest, second fastest and most robust rate are reduced to 2 FOR-loop.

The sorted list of rates according throughput is extended to the best four
rates as we need them in upcoming joint rate and power control. The sorting
is done via the new function minstrel_ht_sort_best_tp_rates(). The annotation
of those 4 best throughput rates in the debugfs file rc-stats is changes to:
"A,B,C,D", where A is the fastest rate and C the 4th fastest.

Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
Tested-by: Stefan Venz <ikstream86@gmail.com>
Acked-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-09-11 12:10:14 +02:00
Antonio Quartulli
cca674d47e mac80211: export the expected throughput
Add get_expected_throughput() API to mac80211 so that each
driver can implement its own version based on the RC
algorithm they are using (might be using an HW RC algo).
The API returns a value expressed in Kbps.

Also, add the new get_expected_throughput() member
to the rate_control_ops structure in order to be
able to query the RC algorithm (this patch provides an
implementation of this API for both minstrel and
minstrel_ht).

The related member in the station_info object is now
filled accordingly when dumping a station.

Cc: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-05-21 09:15:16 +02:00
Johannes Berg
00591cea31 mac80211: minstrel-ht: small clarifications
Antonio and I were looking over this code and some things
didn't immediately make sense, so we came up with two small
clarifications.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-05-19 14:30:37 +02:00
Johannes Berg
f6e1a73b66 mac80211: minstrel_ht: sample_table can be __read_mostly
The sample table is initialized only once at module start, so
is really __read_mostly. Additionally, the code to init it can
be marked __init since it will never be needed again, it is
likely automatically inlined into the __init function already
by the compiler, so this doesn't really make a difference.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-02-04 21:48:25 +01:00
Johannes Berg
631ad703ba mac80211: make rate control ops const
Change the code to allow making all the rate control ops
const, nothing ever needs to change them. Also change all
drivers to make use of this and mark the ops const.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2014-02-04 21:48:21 +01:00
Weilong Chen
f359d3fe83 mac80211: fix checkpatch errors
Fix a number of different checkpatch errors.

Signed-off-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-12-18 10:33:06 +01:00
John W. Linville
e08fd975bf Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless
Conflicts:
	drivers/net/wireless/brcm80211/Kconfig
	net/mac80211/util.c
2013-12-06 09:50:45 -05:00
Karl Beldan
f12140c04c mac80211: minstrel_ht: do not sample unsupported rates
ATM minstrel_ht does not check whether a sampling rate is supported.
Unsupported rates attempts can trigger when there are holes in bitfields
of supported MCSes belonging to the same group (e.g many devices are
MCS32 capable without MCS33->39 capable, also we systematically have a
hole for CCK rates).
Drop any attempts to sample unsupported rates, as suggested by Felix.

This is not a problem in minstrel which fills a per STA sample table
with only supported rates (though only at init).

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-11-25 20:52:21 +01:00
Karl Beldan
f7d8ad81ca mac80211: minstrels: spare numerous useless calls to get_random_bytes
ATM, only the first array value returned by get_random_bytes is used.
This change moves the call to get_random_bytes from the nested loop it
is in to its parent.
While at it, replace get_random_bytes with prandom_bytes since PRNs are
way enough for the selection process.
After this, minstrel_ht reclaims 80 PR-bytes instead of 640 R-bytes.

minstrels use sample tables to probe different rates in a randomized
manner.
minstrel_ht inits one single sample table upon registration (during
subsys_initcalls) and minstrel uses one per STA addition in minstrel.

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-11-25 20:52:09 +01:00
Karl Beldan
7a5e3fa2c8 mac80211: minstrel_ht: replace some occurences of MCS_GROUP_RATES
Consecutive MCSes in [8*(NSS-1)->8*NSS[ have the same number NSS of
streams (except for MCS32 which is mishandled ATM).
ATM minstrel_ht uses MCS_GROUP_RATES in place of this 8 modulus.
This change replaces such occurences and by doing so allows for different
values of MCS_GROUP_RATES (e.g to cope with VHT MCS8,9).

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-11-25 20:52:07 +01:00
Karl Beldan
5664da4429 mac80211: use capped prob when computing throughputs
Commit 3e8b1eb "mac80211/minstrel_ht: improve rate selection stability"
introduced a local capped prob in minstrel_ht_calc_tp but omitted to use
it to compute the per rate throughput.

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Cc: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-11-25 16:56:17 +01:00
Karl Beldan
351df09972 mac80211: minstrel_ht: fix rates selection
When initializing rates selections starting indexes upon stats update,
the minstrel_sta->max_* rates should be 'group * MCS_GROUP_RATES + i'
not 'i'. This affects settings where one of the peers does not support
any of the rates of the group 0 (i.e. when ht_cap.mcs.rx_mask[0] == 0).

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Acked-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-11-25 16:50:10 +01:00
Lorenzo Bianconi
37feb7e2fb mac80211: do not override fixed_rate_idx in minstrel_ht_update_stats
Do not override max_tp_rate, max_tp_rate2 and max_prob_rate configured
according to fixed_rate in minstrel_ht_update_stats throughput computation

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
Acked-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-09-26 13:27:12 +02:00
John W. Linville
f3e979a52c Merge branch 'for-john' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next 2013-08-28 13:51:40 -04:00
John W. Linville
b35c809708 Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless
Conflicts:
	drivers/net/wireless/iwlwifi/pcie/trans.c
	net/mac80211/ibss.c
2013-08-28 10:36:09 -04:00
Johannes Berg
e133fae263 mac80211: minstrel_ht: don't use control.flags in TX status path
Sujith reports that my commit af61a16518
("mac80211: add control port protocol TX control flag") broke ath9k
(aggregation). The reason is that I made minstrel_ht use the flag in
the TX status path, where it can have been overwritten by the driver.
Since we have no more space in info->flags, revert that part of the
change for now, until we can reshuffle the flags or so.

Reported-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-08-22 08:37:08 +02:00
Felix Fietkau
2dfca312a9 mac80211: add a flag to indicate CCK support for HT clients
brcm80211 cannot handle sending frames with CCK rates as part of an
A-MPDU session. Other drivers may have issues too. Set the flag in all
drivers that have been tested with CCK rates.

This fixes a reported brcmsmac regression introduced in
commit ef47a5e4f1aaf1d0e2e6875e34b2c9595897bef6
"mac80211/minstrel_ht: fix cck rate sampling"

Cc: stable@vger.kernel.org # 3.10
Reported-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-08-21 15:03:25 +02:00
John W. Linville
d074666366 Merge branch 'for-john' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next 2013-08-16 14:24:51 -04:00
Johannes Berg
af61a16518 mac80211: add control port protocol TX control flag
A lot of drivers check the frame protocol for ETH_P_PAE,
for various reasons (like making those more reliable).
Add a new flags bitmap to the TX control info and a new
flag indicating the control port protocol is in use to
let all drivers also apply such logic to other control
port protocols, should they be configured.

Also use the new flag in the iwlwifi drivers.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-08-12 14:09:29 +02:00
John W. Linville
7546ff9549 Merge branch 'for-john' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next 2013-08-01 15:26:52 -04:00
Simon Wunderlich
438b61b770 mac80211: fix timing for 5 MHz and 10 MHz channels
according to IEEE 802.11-2012 section 18, various timings change
when using 5 MHz and 10 MHz. Reflect this by using a "shift" when
calculating durations.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
2013-07-16 09:58:04 +03:00
Simon Wunderlich
3de805cf96 mac80211/rc80211: add chandef to rate initialization
5 and 10 MHz support needs to know the current operating channel width,
add the chandef to the rate control API.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
2013-07-16 09:58:02 +03:00
Felix Fietkau
1cd1585739 mac80211/minstrel_ht: fix cck rate sampling
The CCK group needs special treatment to set the right flags and rate
index. Add this missing check to prevent setting broken rates for tx
packets.

Cc: stable@vger.kernel.org # 3.10
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
2013-07-16 09:55:56 +03:00
Felix Fietkau
a85666627b mac80211/minstrel_ht: use the new rate control API
Pass the rate selection table to mac80211 from minstrel_ht_update_stats.
Only rates for sample attempts are set in info->control.rates.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-04-22 16:16:41 +02:00
Karl Beldan
a36473621c mac80211: minstrel_ht: initialize rates selection
Initialize {mp,mi}->{max_tp_rate,max_tp_rate2,max_prob_rate} in
minstrel_ht's rate_init and rate_update.

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-04-22 15:47:12 +02:00
Karl Beldan
c2eb5b0f34 mac80211: minstrel_ht: pick only supported rates for sta and group max*rates
minstrel_ht initializes max_tp_rate max_tp_rate2 and max_prob_rate to
zero both for minstrel_ht_sta and minstrel_mcs_group_data.
This is wrong since there is no guarantee that the 1st rate of any
group is supported.

Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-04-22 15:47:12 +02:00
Felix Fietkau
a0ca796c46 mac80211/minstrel_ht: do not sample actively used rates
max_tp_rate2 and max_prob_rate tend to get used occasionally during
retransmission, which is more useful for the statistics than probing
with individual probe packets.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-03-18 20:11:58 +01:00
Felix Fietkau
bc96f24266 mac80211/minstrel_ht: avoid useless sampling of high-probability slower rates
Slow rates that have >95% success probability do not need to be
monitored continuously. When the channel conditions change rapidly, the
slow sampling results are useless anyway. When conditions change slowly,
they will be monitored by gradual downgrading of the actively used
rates. This patch slightly improves throughput under good conditions.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-03-18 20:11:58 +01:00
Felix Fietkau
3e8b1eb21c mac80211/minstrel_ht: improve rate selection stability
Under load, otherwise stable rates can easily fluctuate because of
collisions. In my tests on a clean channel, the success probability of
the max throughput rate often stays somewhere between 90% and 100% under
load. This can cause some unnecessary switching to lower rates.
This patch improves stability by treating success probability values
between 90% and 100% the same.
In my tests on a 3x3 HT20 link with lots of TCP traffic, it improves the
average throughput by a few mbit/s.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-03-18 20:11:58 +01:00
Thomas Huehn
f744bf81f7 mac80211: add lowest rate into minstrel's random rate sampling table
While minstrel bootstraps and fills the success probabilities of each
rate the lowest rate has typically a very high success probability
(often 100% in our tests).
Its statistics are never updated but considered to setup the mrr chain.
In our tests we see that especially the 3rd mrr stage (which is that
rate providing highest success probability) is filled with the lowest rate
because its initial high sucess probability is never updated. By design
the 4th mrr stage is filled with the lowest rate so often 3rd and 4th
mrr stage are equal.

This patch follows minstrels general approach of assuming as little
as possible about rate dependencies. Consequently we include the
lowest rate into the random sampling table to get balanced up-to-date
statistics of all rates and therefore balanced decisions.

Acked-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-03-06 16:36:09 +01:00
Thomas Huehn
a512d4b543 mac80211: merge EWMA calculation of minstrel_ht and minstrel
Both rate control algorithms (minstrel and minstrel_ht) calculate
averages based on EWMA. Shift function minstrel_ewma() into
rc80211_minstrel.h and make use of it in both minstrel version.
Also shift the default EWMA level (75%) definition to the header file
and clean up variable usage.

Acked-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-03-06 16:36:06 +01:00
Felix Fietkau
52c00a37a3 mac80211/minstrel_ht: disable multiple consecutive sample attempts
The last minstrel_ht changes increased the sampling frequency for
potentially useful rates to decrease the response time to rate
fluctuations. This caused an increase in sampling frequency that can
slightly reduce throughput, so this patch limits the sampling attempts
to one per rate instead of two.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2013-03-06 16:36:06 +01:00