System freezes with high network activity

From: Jose Luis Salas
Date: Fri Dec 02 2011 - 11:44:26 EST


Hello there,

I' ve filled a bug against linux kernel in Debian [1] for the
linux-kernel-image 2.6.32.

The problem is that the system freezes ( no complete ) when high
network activity occurrs, for example copying files over NFS or
downloading files with Bittorrent.

When the system is frozen, there is no network connecivity, the
console freezes ( with top program, for ex. ) until a key from the
laptop is pressed or when network activity drops. The network
throughtput also drops before the freeze.

I've also realized that clock drifts ( it's frozen too ) when the
system is frozen.

This problem didn't occur in Linux kernel 2.6.26 ( from the Lenny
release ), I think >2.6.26 are affected, but I need to confirm it ( >=
2.6.30 are included for sure ).

After investigating for a while ( tested noapic, noacpi and several
switches with no luck.) , I've search for a solution and I finally
found it. I think that the bug is caused by changes in the
clocksource between kernels and the powernow-k8 module.

One time I tested booting the xen-patched the linux kernel and the
problem dissapeared, the net worked at full speed but there was no cpu
scaling.

Now, with recent kernels, I boot the kernel with the
clocksource=jiffies option and the powersaved daemon to do the
frequency scaling, the net works al full speed. With acpi_pm and tsc
options doesn't work neither.

More information as acpidump output and dmesg are included in the [1]
Debian bug too.

Thanks.

[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=583363
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