I've been noticing this symptom for a while now especially when running programs that copy large files using large buffer sizes.  It's worse than just firefox, as the entire desktop will freeze for minutes at a time.

This change/workaround cleared this up entirely for me.  If we haven't incorporated this yet, we should consider doing so.

-------- Original Message --------
Subject: Re: [Cooker] System can stall under heavy IOs with slow storage devices
Date: Mon, 19 Dec 2011 19:36:02 +0100
From: Florian Hubold <doktor5000@arcor.de>
Reply-To: cooker@mandrivalinux.org
To: cooker@mandrivalinux.org


Am 19.12.2011 10:26, schrieb Franck Bui:
> Hello,
>
> I've noticed a regression on my system which can stall some applications
> (most notably firefox) during very very long time (> 10 mins).
Man, you're my hero, trying to find out what causes this since some months now.
At least two thumbs up! :)
> It's apparently related to transparent huge pages and I found that it
> had already been described by LWN here a month ago:
> http://lwn.net/Articles/467328/.
>
> Unlike what it's stated in the article, the regression is not really
> hard to trigger in my case: just plug a USB stick, copy on it a big
> file, then try to use firefox...
>
> To fix this, simply try to disable THP:
>
>   echo madvise >/sys/kernel/mm//transparent_hugepage/enabled
>
> and firefox should work as expected now.
>
> So, if no one objects, the plan is to simply default the THP stuff to
> "madvise" for desktop flavour where an application has to ask
> explicitly huge page otherwise it will be disabled.
>