Opened 20 months ago

Last modified 20 months ago

#22445 new defect

Regression CC vs BB release: Low WiFi speed when increasing coverage class

Reported by: xback Owned by: developers
Priority: normal Milestone:
Component: packages Version: Chaos Calmer 15.05
Keywords: ath9k, mac80211, minstrel Cc:



Chaoscalmer has a lot less wifi bandwidth when coverage class is increased.
Even when 2 devices are only a few meters apart.

In Barrierbreaker release, the rates were a lot higher in this usecase.

When doing Iperf benchmarks (~ 30 sec);

  • The barrierbreaker release is able to hit ~53Mbit from start to finish
  • Chaoscalmer starts at ~6Mbit/s, than slowly goes up to ~20Mbit/s. But starts at 6 again when the test is repeated.

Following setup:

  • 2 identical devices
  • IBSS mode using wpa_supplicant WPA2
  • 2m apart
  • Free 5GHz channel (confirmed using spectrum analyzer)
  • HT20 (HT40 has same behaviour)
  • Coverage class 32 (up to 14400m)

Iperf using BarrierBreaker build: ~52Mbit/s
Iperf using ChaosCalmer build: ~6Mbit/s

  • Coverage class 16 (up to 7200m)

Iperf using BarrierBreaker build: ~53Mbit/s
Iperf using ChaosCalmer build: ~12Mbit/s

  • Dynack

Iperf using BarrierBreaker build: ~55Mbit/s
Iperf using ChaosCalmer build: ~53Mbit/s

Steps I tested to identify the issue without success:

  • Upgraded wpa_supplicant to latest trunk
  • Checked ath9k code hw.c & recv.c (Acktime, slottime, etc. But code doesnt differ between BB and CC)
  • Patches deleted: (in kernel/mac80211/patches)

--> 326-ath9k-make-NF-load-complete-quickly-and-reliably.patch
--> 330-mac80211-minstrel-Change-expected-throughput-unit-ba.patch
--> 334-mac80211-fix-wiphy-supported_band-access.patch
--> 335-mac80211-minstrel_ht-set-A-MSDU-tx-limits-based-on-s.patch
--> 336-mac80211-minstrel_ht-set-default-tx-aggregation-time.patch
--> 337-mac80211-minstrel_ht-fix-a-logic-error-in-RTS-CTS-ha.patch
--> 343-mac80211-minstrel_ht-improve-sample-rate-skip-logic.patch

Only part in the chain that I still need to check:

  • Minstrel_ht

If more information is required, please let me know.



Attachments (0)

Change History (1)

comment:1 Changed 20 months ago by xback

Other stuff tested:

  • Force-disable wpa_supplicant background scanning

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