Re: frequent lockups in 3.18rc4

From: Andy Lutomirski
Date: Fri Nov 21 2014 - 14:52:54 EST

On Fri, Nov 21, 2014 at 11:46 AM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Fri, Nov 21, 2014 at 11:34 AM, Linus Torvalds
> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>> So I kind of agree, but it wouldn't be my primary worry. My primary
>> worry is actually paravirt doing something insane.
> Btw, on that tangent, does anybody actually care about paravirt any more?

Amazon, for better or for worse.

> I'd love to start moving away from it. It makes a lot of the low-level
> code completely impossible to follow due to the random indirection
> through "native" vs "paravirt op table". Not just the page table
> handling, it's all over.
> Anybody who seriously does virtualization uses hw virtualization that
> is much better than it used to be. And the non-serious users aren't
> that performance-sensitive by definition.
> I note that the Fedora kernel config seems to include paravirt by
> default, so you get a lot of the crazy overheads..

I think that there is a move toward deprecating Xen PV in favor of
PVH, but we're not there yet.

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