Comment 1 for bug 383332

First time poster. I'm experiencing very similar symptoms. The system monitor shows my cached memory soaring to fill the entirety of my ram. I can manually reset my cached ram with

sync; echo 3 > /proc/sys/vm/drop_caches

from the command line, which has about 75% effectiveness of putting off the memory lag. The cached memory immediately begins to build up again, and it seems to only happen when I'm file-sharing.

$ lsb_release -rd
Description: Ubuntu 9.04
Release: 9.04

 uname -a
Linux kyler-laptop 2.6.28-15-generic #52-Ubuntu SMP Wed Sep 9 10:49:34 UTC 2009 i686 GNU/Linux

lspci -vvnn
## relevant output only
08:00.0 Network controller [0280]: Intel Corporation PRO/Wireless 5300 AGN [Shiloh] Network Connection [8086:4235]
 Subsystem: Intel Corporation Device [8086:1001]
 Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
 Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
 Latency: 0, Cache Line Size: 64 bytes
 Interrupt: pin A routed to IRQ 2295
 Region 0: Memory at f2100000 (64-bit, non-prefetchable) [size=8K]
 Capabilities: <access denied>
 Kernel driver in use: iwlagn
 Kernel modules: iwlagn