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Date: Fri, 21 Nov 2014 11:46:57 -0800
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Subject: Re: frequent lockups in 3.18rc4
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Andy Lutomirski <luto@amacapital.net>, Tejun Heo <tj@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
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        Peter Zijlstra <peterz@infradead.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Don Zickus <dzickus@redhat.com>, Dave Jones <davej@redhat.com>,
        "the arch/x86 maintainers" <x86@kernel.org>
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On Fri, Nov 21, 2014 at 11:34 AM, Linus Torvalds
<torvalds@linux-foundation.org> 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?

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..

                   Linus