Re: 2.6.38: rt2800usb: high latency (1000ms)?

From: Igor Plyatov
Date: Thu Apr 14 2011 - 01:39:10 EST

Dear Daniel,
On Wed, Apr 13, 2011 at 1:13 PM, Justin Piszcz<jpiszcz@xxxxxxxxxxxxxxx> wrote:
(1) What is the AP's beacon period and DTIM? Typical values are 100
TUs for beacons (102.4 ms) and 2 for DTIM (2 beacons per power-save
wakeup) which should imply a mean of 100 and max of 200 ms delay even
on pings.
I am using a WNDR3700 with default settings in terms of beacons/etc. No
issues with any device (laptop, computer, etc (in windows)), I have two
wireless USB adapters (bought two) and in Windows, no problems, I don't
it is the WNDR3700. As far as linux/wpa-supplicant, using default settings.
Not enough info. What does "iw dev wlan1 scan dump" (it might not be
wlan1 for you) say for "beacon interval"?

Does anyone know how to get the DTIM period out of iw?

# iw dev wlan0 scan dump
BSS 74:ea:3a:e4:fa:6e (on wlan0) -- associated
TSF: 499843461 usec (0d, 00:08:19)
freq: 2442
beacon interval: 100
capability: ESS Privacy ShortPreamble ShortSlotTime (0x0431)
signal: -51.00 dBm
last seen: 510 ms ago
Information elements from Probe Response frame:
SSID: mynet2
Supported rates: 1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0
DS Parameter set: channel 7
RSN: * Version: 1
* Group cipher: CCMP
* Pairwise ciphers: CCMP
* Authentication suites: PSK
* Capabilities: (0x0000)
ERP: <no flags>
Extended supported rates: 24.0 36.0 48.0 54.0
WMM: * Parameter version 1
* u-APSD
* BE: CW 15-1023, AIFSN 3
* BK: CW 15-1023, AIFSN 7
* VI: CW 7-15, AIFSN 2, TXOP 3008 usec
* VO: acm CW 3-7, AIFSN 2, TXOP 1504 usec
HT capabilities:
Capabilities: 0x104e
SM Power Save disabled
Max AMSDU length: 3839 bytes
Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
Minimum RX AMPDU time spacing: 8 usec (0x06)
HT RX MCS rate indexes supported: 0-15
HT TX MCS rate indexes are undefined
WPS: * Version: 1.0
* Wi-Fi Protected Setup State: 2 (Configured)
* Response Type: 3 (AP)
* Unknown TLV (0x1047, 16 bytes): 00 00 00 00 00 00 10 00 00 00 74 ea 3a e4 fa 6e
* Manufacturer: TP-LINK
* Model: TL-WR1043N
* Model Number: 1.0
* Serial Number: 1.0
* Primary Device Type: 6-0050f204-1
* Device name: Wireless Router TL-WR1043N
* Config methods: Ethernet, Label, PBC
* RF Bands: 0x1

(2) How long does the client wait after waking up to go back to sleep?
It should be at least a few seconds. For ssh, then, you should see
something like a 100-200 ms delay for the first key and then nothing
at all unless you stop typing for a bit.
It lags with each word I type, it is terrible. If I run something like
dmesg or ps auxww, the entire session freezes for 5-10 seconds before it
comes back.
Sorry; I meant what is the software stack configured to do? Do some
looking around.
What do you mean here?

Best regards!
Igor Plyatov
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