Discussion:
mbuf leak on NetBSD-5 AP when Windows laptop connects
(too old to reply)
Roy Marples
2009-08-13 08:36:37 UTC
Permalink
Hi List!

I've been running NetBSD-5 on my Access Point for some time, with great
success.
However, when a Windows based laptop connects to the network, the AP
runs out of mbufs in about 45 minutes. This is 100% reproducable with
minimal traffic from laptop -> AP. When the laptop is turned off, the AP
is fine and has no trouble talking to my other boxes (1 laptop, 2
desktops, 1 wii).

I have attached an mbuf watchdog script that runs as a cron job every 5
minutes to check that total claimed mbufs do not exceed 1000 - if it
does, it restarts the AP interface. Currently, it is emailing me every
15 minutes.
Here is some sample output

1059 mbufs in use:
1033 mbufs allocated to data
24 mbufs allocated to packet headers
2 mbufs allocated to socket names and addresses
4 calls to protocol drain routines
mbufs exceed 1000 - restarting ath0


The AP tracks the netbsd-5 branch and is an amd64 with an ath(4)
wireless network card.
This behaviour was present both before and after the pullup was made to
bring the new ath HAL into netbsd-5.
The AP also runs PF, PPPoE and ALTQ in the kernel.
options MBUFTRACE has been enabled and only "unknown data" is growing,
which is of no help for working out where the problem lies.

The Windows laptop is a Lenovo T500 with an Intel Wifi Link 5100 AGN
network card. It ran Vista32 an now Windows7 64, both with this problem.
Roy Marples
2009-09-01 20:58:55 UTC
Permalink
Post by Roy Marples
Hi List!
I've been running NetBSD-5 on my Access Point for some time, with great
success.
However, when a Windows based laptop connects to the network, the AP
runs out of mbufs in about 45 minutes. This is 100% reproducable with
minimal traffic from laptop -> AP. When the laptop is turned off, the AP
is fine and has no trouble talking to my other boxes (1 laptop, 2
desktops, 1 wii).
I have attached an mbuf watchdog script that runs as a cron job every 5
minutes to check that total claimed mbufs do not exceed 1000 - if it
does, it restarts the AP interface. Currently, it is emailing me every
15 minutes.
Here is some sample output
1033 mbufs allocated to data
24 mbufs allocated to packet headers
2 mbufs allocated to socket names and addresses
4 calls to protocol drain routines
mbufs exceed 1000 - restarting ath0
The AP tracks the netbsd-5 branch and is an amd64 with an ath(4)
wireless network card.
This behaviour was present both before and after the pullup was made to
bring the new ath HAL into netbsd-5.
The AP also runs PF, PPPoE and ALTQ in the kernel.
options MBUFTRACE has been enabled and only "unknown data" is growing,
which is of no help for working out where the problem lies.
The Windows laptop is a Lenovo T500 with an Intel Wifi Link 5100 AGN
network card. It ran Vista32 an now Windows7 64, both with this problem.
I've now tracked this down to altq - either used in pf OR altqd alongside
ipfilter.

Would a tcpdump help track this down further?

Thanks

Roy

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