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Date: Wed, 13 Jun 2018 17:08:13 +0200
From: Greg KH <gregkh@linuxfoundation.org>
To: Paul Hedderly <paul@mjr.org>
Subject: Re: Kernel lockup with (debian) 4.16.0-2-rt-amd64
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On Wed, Jun 13, 2018 at 03:54:24PM +0100, Paul Hedderly wrote:
> On Wed, 2018-06-13 at 15:52 +0200, Jason A. Donenfeld wrote:
> > Hi Paul,
> > 
> > I got an -rt kernel up and running, enabled a bunch of nice debugging
> > options, and found a handful of problems, all of which were fixed by:
> > https://git.zx2c4.com/WireGuard/commit/?id=0f05452d043d8d047cf5d7987f
> > c2732b97d676e6
> > 
> > I realize the solution in that patch is a bit of a bummer, but at the
> > very least it keeps things from breaking now. I'll see if I can
> > improve it somewhere down the line.
> 
> OUch. "So on sane kernels" I guess RT isn't sane then!
> 
> Yea that performance hit is a nuisance, although in reality when I
> really need RT I wont be doing much over a VPN... so I may have to suck
> up to rebooting between kernels for a while. No big deal.

Note, the -rt kernels _always_ run slower than a non-rt kernel.  Real
time is not "faster", it is only "deterministic".  And it achieves this
goal at the expense of performance, which is the only way it can be
done.

So I recommend just trying the "normal" kernel instead, odds are it will
work just fine for you, unless you have some _very_ specific max-bound
latency issues.

thanks,

greg k-h