linux-kernel - Re: frequent lockups in 3.18rc4

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 21 Nov 2014 15:23:13 -0500
From:	Josh Boyer <jwboyer@...oraproject.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Tejun Heo <tj@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Don Zickus <dzickus@...hat.com>, Dave Jones <davej@...hat.com>,
	"the arch/x86 maintainers" <x86@...nel.org>
Subject: Re: frequent lockups in 3.18rc4

On Fri, Nov 21, 2014 at 3:16 PM, Andy Lutomirski <luto@...capital.net> wrote:
> On Fri, Nov 21, 2014 at 12:14 PM, Josh Boyer <jwboyer@...oraproject.org> wrote:
>> On Fri, Nov 21, 2014 at 2:52 PM, Andy Lutomirski <luto@...capital.net> wrote:
>>> On Fri, Nov 21, 2014 at 11:46 AM, Linus Torvalds
>>> <torvalds@...ux-foundation.org> wrote:
>>>> On Fri, Nov 21, 2014 at 11:34 AM, Linus Torvalds
>>>> <torvalds@...ux-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.
>
> A move in the Xen project.  As I understand it, Xen wants to deprecate
> PV in favor of PVH, but PVH is still experimental.

OK.

> I think that dropping PARAVIRT in Fedora might be a bad idea for
> several more releases, since that's likely to break the EC2 images.

Yes, that's essentially the only reason we haven't looked at disabling
Xen completely for a while now, so <sad trombone>.

josh
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/