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Ticket #2140 (new defect)

Opened 13 years ago

Last modified 13 years ago

Packet's don't go out under high load

Reported by: dagrawal@cs.umass.edu Assigned to:
Priority: major Milestone:
Component: madwifi: driver Version: v0.9.3.2
Keywords: outgoing packets freeze Cc:
Patch is attached: 0 Pending: 0

Description (Last modified by mrenzmann)

Hello,

I am using madwifi-0.9.3.2 in adhoc mode. Under high load (ie when there is a lot of ongoing traffic), I experience the following problem:

Although tc -s qdisc dev show wifi0 shows that many KB's of packets are backlogged, and my UDP socket queues are also full. I can't see any outgoing packets. I verify this problem by

a) doing a tcpdump -i ath0 "ip src 100.0.0.X" on the offending node (whose IP is 100.0.0.X), and on some neighboring node (that can hear X). I see nothing going out.

This happens erratically, ie it may or may not happen all the time. This makes it all the more perplexing. I have a twenty node testbed, and it seems to happen randomly on any one of them.

And sometimes, this only happens if I am sending Non best effort packets out. Like by doing ping -Q 0x08 (or even with the voice queue 0x30 etc). But sometimes, this affects all outgoing packets, even best effort ones.

The problem disappears after a long time on its own, of the order of half to a couple of hours.

Here is my relevant system info: (Ubuntu 7.10 on an intel mac mini)

lspci -vv:

02:00.0 Ethernet controller: Atheros Communications, Inc. Unknown device 001c (rev 01)
	Subsystem: Apple Computer Inc. Unknown device 0086
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR-
	Latency: 0, Cache Line Size: 256 bytes
	Interrupt: pin A routed to IRQ 16
	Region 0: Memory at 90100000 (64-bit, non-prefetchable) [size=64K]
	Capabilities: [40] Power Management version 2
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
		Status: D0 PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [50] Message Signalled Interrupts: Mask- 64bit- Queue=0/0 Enable-
		Address: 00000000  Data: 0000
	Capabilities: [60] Express Legacy Endpoint IRQ 0
		Device: Supported: MaxPayload 128 bytes, PhantFunc 0, ExtTag-
		Device: Latency L0s <512ns, L1 <64us
		Device: AtnBtn- AtnInd- PwrInd-
		Device: Errors: Correctable- Non-Fatal- Fatal- Unsupported-
		Device: RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop-
		Device: MaxPayload 128 bytes, MaxReadReq 512 bytes
		Link: Supported Speed 2.5Gb/s, Width x1, ASPM L0s L1, Port 0
		Link: Latency L0s <512ns, L1 <64us
		Link: ASPM Disabled RCB 128 bytes CommClk+ ExtSynch-
		Link: Speed 2.5Gb/s, Width x1
	Capabilities: [90] MSI-X: Enable- Mask- TabSize=1
		Vector table: BAR=0 offset=00000000
		PBA: BAR=0 offset=00000000
	Capabilities: [100] Advanced Error Reporting
	Capabilities: [140] Virtual Channel

iwconfig:

ath0      IEEE 802.11b  ESSID:"XYZ"  Nickname:""
          Mode:Ad-Hoc  Frequency:2.437 GHz  Cell: Not-Associated   
          Bit Rate=11 Mb/s   Tx-Power=15 dBm   Sensitivity=1/1  
          Retry:off   RTS thr:off   Fragment thr:off
          Encryption key:XYZ   Security mode:restricted
          Power Management:off
          Link Quality=16/70  Signal level=-80 dBm  Noise level=-96 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

Are you folks aware of this problem? Has it been rectified in 0.9.4 version? Or is it because I am doing something wrong. Thanks.

I would be grateful for your advise.

Change History

09/21/08 17:38:30 changed by mrenzmann

  • description changed.

09/22/08 00:14:30 changed by dagrawal@cs.umass.edu

Hi, I would like to add that the exact same problem happens with the latest 0.9.4 version also.

03/09/09 03:33:03 changed by iluxa

I'm seeing similar problem in AP mode. The trigger is probe request packet storm.