linux-kernel - Re: System freezes with high network activity

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Message-ID: <1322855029.21423.170.camel@work-vm>
Date:	Fri, 02 Dec 2011 11:43:49 -0800
From:	john stultz <johnstul@...ibm.com>
To:	Jose Luis Salas <josacar@...il.com>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Jonathan Nieder <jrnieder@...il.com>
Subject: Re: System freezes with high network activity

On Fri, 2011-12-02 at 17:44 +0100, Jose Luis Salas wrote:
> 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.

So, could you attach a full dmesg when you're not using
clocksource=jiffies?

Also, when not using clocksource=jiffies, does booting with nohz=off
change the behavior?

thanks
-john


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