Hostapd ACS not changing from previously selected channel

Fumikazu Yobimoto fyobimoto at chromium.org
Fri Feb 20 20:00:38 EST 2015


Hi,

>SALT# hostapd -d /etc/hostapd/hostapd.conf | grep ACS
>ACS: Automatic channel selection started, this may take a bit
>ACS: Scanning 1 / 5
>wlan1: interface state COUNTRY_UPDATE->ACS
>wlan1: ACS-STARTED
>Interface initialization will be completed in a callback (ACS)
>ACS: Using survey based algorithm (acs_num_scans=5)
>ACS: Scanning 2 / 5
>ACS: Using survey based algorithm (acs_num_scans=5)
>ACS: Scanning 3 / 5
>ACS: Using survey based algorithm (acs_num_scans=5)
>ACS: Scanning 4 / 5
>ACS: Using survey based algorithm (acs_num_scans=5)
>ACS: Scanning 5 / 5
>ACS: Using survey based algorithm (acs_num_scans=5)
>ACS: Trying survey-based ACS
>ACS: Survey analysis for channel 13 (2472 MHz)
>ACS: 1: min_nf=-98 interference_factor=0.00909091 nf=-98 time=110 busy=1
>rx=0
>ACS: 2: min_nf=-98 interference_factor=0.00900901 nf=-98 time=111 busy=1
>rx=1
>ACS: 3: min_nf=-98 interference_factor=0.0540541 nf=-98 time=111 busy=6
rx=3
>ACS: 4: min_nf=-98 interference_factor=2.51189e-20 nf=-98 time=111
>busy=0 rx=0
>ACS: 5: min_nf=-98 interference_factor=2.51189e-20 nf=-98 time=111
>busy=0 rx=0


This log indicates that other channels(ch.1-12) would be disabled for some
reason.
Normally, log shows all channel's survey result, but it seems only one
channel.
Another example 6.ch case would be same similarly.
Inference is ath5k driver doesn't send all channel's valid survey date when
it set defined channel previously, as you said.
Can you check the log about 'nl80211', you can see it as following.

$ hostapd -d hostapd.conf | grep nl80211


Sample(partial log)
===
nl80211: Scan included frequencies: 2412 2417 2422 2427 2432 2437 2442 2447
2452 2457 2462
nl80211: Fetch survey data
nl80211: Freq survey dump event (freq=2412 MHz noise=-91 channel_time=167
busy_time=0 tx_time=0 rx_time=126 filled=000b)
nl80211: Freq survey dump event (freq=2417 MHz noise=-91 channel_time=167
busy_time=0 tx_time=0 rx_time=123 filled=000b)
nl80211: Freq survey dump event (freq=2422 MHz noise=-91 channel_time=167
busy_time=0 tx_time=0 rx_time=116 filled=000b)
nl80211: Freq survey dump event (freq=2427 MHz noise=-92 channel_time=167
busy_time=0 tx_time=0 rx_time=85 filled=000b)
nl80211: Freq survey dump event (freq=2432 MHz noise=-91 channel_time=167
busy_time=0 tx_time=0 rx_time=23 filled=000b)
nl80211: Freq survey dump event (freq=2437 MHz noise=-92 channel_time=167
busy_time=0 tx_time=0 rx_time=16 filled=000b)
nl80211: Freq survey dump event (freq=2442 MHz noise=-92 channel_time=167
busy_time=0 tx_time=0 rx_time=17 filled=000b)
nl80211: Freq survey dump event (freq=2447 MHz noise=-92 channel_time=167
busy_time=0 tx_time=0 rx_time=24 filled=000b)
nl80211: Freq survey dump event (freq=2452 MHz noise=-92 channel_time=167
busy_time=0 tx_time=0 rx_time=41 filled=000b)
nl80211: Freq survey dump event (freq=2457 MHz noise=-93 channel_time=167
busy_time=0 tx_time=0 rx_time=41 filled=000b)
nl80211: Freq survey dump event (freq=2462 MHz noise=-92 channel_time=167
busy_time=0 tx_time=0 rx_time=44 filled=000b)
===

Yobi
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