[Lustre-discuss] kernel: BUG: soft lockup - CPU stuck for 10s! with lustre 1.8.4

[Peter Jones]

Yes, turning off statahead is a workaround. Of course it is a trade-off 
and ultimately for you to decide. However,  the statahead feature 
(introduced in 1.6.2 I think) has been very problematic and many 
previous attempts at fixing issues have caused subtle regressions. Most 
sites seem to be able to run statahead ok with the latest 1.8.x releases 
so I think that we are just down to edge cases. We will of course still 
continue to remove the edge cases in future releases, and perhaps 
FanYong's patch might land and be tested out as part of a release, but, 
as things stand, this is still just a proposed fix. If you do decide to 
try the patch, please post your experiences to the bz ticket - thanks!

Temple Jason wrote:
> It appears that turning off statahead does indeed avoid the soft lockup bug.  But this seems to me to be a workaround, and not a solution.
>
> Is statahead not useful for performance gains?  I am not comfortable making my user's jobs waste more cpu time because I have to implement a workaround instead of a fix.
>
> Is there one in the works?  Nasf - does your patch solve the bug, or does it just disable statahead by default?
>
> Thanks,
>
> Jason
>
>
>