lkml.org 
[lkml]   [2020]   [Jan]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [tip: core/rcu] rcu: Enable tick for nohz_full CPUs slow to provide expedited QS
On Sat, Jan 25, 2020 at 08:10:50AM -0800, Paul E. McKenney wrote:
> How big? (Seriously, given that the fix may depend on the number of CPUs.)

[ 7.660017] smp: Brought up 2 nodes, 256 CPUs

> So the problem appears to be that some of the boot-time processing
> is looping in the kernel, which is preventing the grace period from
> completing. One could argue that such code should be fixed, but on the
> other hand, boot time is a bit special. Later in -rcu's dev branch,
> there are commits that forgive this boot-time misbehavior, but this is
> a bit late in process to dump all of those commits into -tip.

Aha.

> The RT guys might need the warning, and it was them that I was thinking
> of when adding it.

But "boot time is a bit special". Or do they care about deadlines during
boot too?

> But let's see what works for mainline first. And
> since your box was booting fine without the warning before, I bet that
> it boots just fine with that warning removed.

Yes, it does.

> So could you please try out the (untested) patch below?

Warning's gone.

> If that works, I will re-introduce the warning with proper protection
> for the merge window following this coming one.

My big box is at your service if you need stuff tested later.

Thx Paul.

--
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette

\
 
 \ /
  Last update: 2020-01-25 18:55    [W:0.057 / U:0.644 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site