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Date: Fri, 21 Nov 2014 15:14:26 -0500
Message-ID: <CA+5PVA4mgpAg53bQKnXXgY3N0mkEZrUYf4rgOTHCV-pbK9UF3g@mail.gmail.com>
Subject: Re: frequent lockups in 3.18rc4
From: Josh Boyer <jwboyer@fedoraproject.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Steven Rostedt <rostedt@goodmis.org>, Tejun Heo <tj@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        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>
Content-Type: text/plain; charset=ISO-8859-1
Sender: linux-kernel-owner@vger.kernel.org

On Fri, Nov 21, 2014 at 2:52 PM, Andy Lutomirski <luto@amacapital.net> wrote:
> On Fri, Nov 21, 2014 at 11:46 AM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>> 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?
>>
>
> 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.

A move where?  The Xen stuff in Fedora is ... not paid attention to
very much.  If there's something we should be looking at turning off
(or on), we're happy to take suggestions.

josh
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