Am 09.03.2013 19:15, schrieb Florian Philipp:
> Hi list!
>
> Whenever I do sequential IO for a long stretch of time (e.g. md5summing
> 40 GB), I'm experiencing high load (ca. 6 on a 4 CPU system) and
> temporary freezes of most applications. For example, switching between
> tabs in konsole sometimes takes more than 2 seconds.
>
> When doing this on an ext4 filesystem, the load seems to result from
> khugepaged and kswapd0 as well as some kworkers.
>
> I think I've had similar issues with NFS over wifi but I cannot test
> this now.
>
> Today I copied 60GB from my hard disk to an USB disk formatted with
> NTFS, issuing the copy command from KDE's dolphin. The freezes became so
> long it was impossible to work and then X11 locked up and had to be killed.
>
> I tried using a preemptive kernel but that didn't seem to help. blkio
> and cpu cgroups didn't help either. Ionice seems to be the only solution
> but while I'm okay with that, my dad won't be. Can anyone tell me what
> is causing this behavior?
>
> Throughput is good, by the way. That's why I don't suspect a driver issue.
>
> Thanks in advance!
> Florian Philipp
>
congratulation. You hit 'the bug'. Been around for ages, but for magical
reasons kernel dev are unable to see or unable to do something about it.
If you are using a vanilla kernel, posting on lkml might be the right
thing to do.
