From: Wei Liu <wei.liu2@citrix.com>
To: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Elena Ufimtseva <elena.ufimtseva@oracle.com>,
Wei Liu <wei.liu2@citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
David Vrabel <david.vrabel@citrix.com>,
Jan Beulich <JBeulich@suse.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: PV-vNUMA issue: topology is misinterpreted by the guest
Date: Fri, 17 Jul 2015 09:44:11 +0100 [thread overview]
Message-ID: <20150717084411.GE12455@zion.uk.xensource.com> (raw)
In-Reply-To: <1437118075.23656.25.camel@citrix.com>
On Fri, Jul 17, 2015 at 09:27:55AM +0200, Dario Faggioli wrote:
> On Fri, 2015-07-17 at 07:09 +0100, Jan Beulich wrote:
> > >>> On 16.07.15 at 18:59, <boris.ostrovsky@oracle.com> wrote:
> > > And in general (both for PV and HVM) --- is there any reason to expose
> > > CPU topology at all? I can see it being useful if VCPUs are pinned but
> > > if they are not then it can make performance worse.
> >
> > Indeed
> >
> Indeed indeed. :-)
>
> And in fact, this is even independent from vNUMA. Yet, I remember we
> were discussing about this since the beginning of vNUMA work, back when
> it was Elena doing it, but the it seems we all forgot... Sorry for
> that! :-/
>
> I seriously think we should do something about this as, while in a non
> vNUMA setup it can certainly cause weird/inconsistent performance, in a
> vNUMA one, as shown, it's quite a hige mess.
>
> > - that's what our kernels have been doing for years, and
> > it seems like someone over here is now looking into whether this
> > could be done in pv-ops too (without too much uglification).
> >
> That would be great, IMO. I'd be up for helping with this, but I know
> next to nothing about CPUID, so that would require some setup time. If,
> at least, you could keep me in the loop it would be great.
>
> In the meanwhile, what should we do? Document this? How? "don't use
> vNUMA with PV guest in SMT enabled systems" seems a bit harsh... Is
> there a workaround we can put in place/suggest?
>
Don't worry. PV vNUMA kernel patch is not upstreamed. :-P
This is one of the issues that is not upstreamed. The other issue is my
own laziness...
Wei.
> Regards,
> Dario
> --
> <<This happens because I choose it to happen!>> (Raistlin Majere)
> -----------------------------------------------------------------
> Dario Faggioli, Ph.D, http://about.me/dario.faggioli
> Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
next prev parent reply other threads:[~2015-07-17 8:44 UTC|newest]
Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-16 10:32 PV-vNUMA issue: topology is misinterpreted by the guest Dario Faggioli
2015-07-16 10:47 ` Jan Beulich
2015-07-16 10:56 ` Andrew Cooper
2015-07-16 15:25 ` Wei Liu
2015-07-16 15:45 ` Andrew Cooper
2015-07-16 15:50 ` Boris Ostrovsky
2015-07-16 16:29 ` Jan Beulich
2015-07-16 16:39 ` Andrew Cooper
2015-07-16 16:59 ` Boris Ostrovsky
2015-07-17 6:09 ` Jan Beulich
2015-07-17 7:27 ` Dario Faggioli
2015-07-17 7:42 ` Jan Beulich
2015-07-17 8:44 ` Wei Liu [this message]
2015-07-17 18:17 ` Boris Ostrovsky
2015-07-20 14:09 ` Dario Faggioli
2015-07-20 14:43 ` Boris Ostrovsky
2015-07-21 20:00 ` Boris Ostrovsky
2015-07-22 13:36 ` Dario Faggioli
2015-07-22 13:50 ` Juergen Gross
2015-07-22 13:58 ` Boris Ostrovsky
2015-07-22 14:09 ` Juergen Gross
2015-07-22 14:44 ` Boris Ostrovsky
2015-07-23 4:43 ` Juergen Gross
2015-07-23 7:28 ` Jan Beulich
2015-07-23 9:42 ` Andrew Cooper
2015-07-23 14:07 ` Dario Faggioli
2015-07-23 14:13 ` Juergen Gross
2015-07-24 10:28 ` Juergen Gross
2015-07-24 14:44 ` Dario Faggioli
2015-07-24 15:14 ` Juergen Gross
2015-07-24 15:24 ` Juergen Gross
2015-07-24 15:58 ` Dario Faggioli
2015-07-24 16:09 ` Konrad Rzeszutek Wilk
2015-07-24 16:14 ` Dario Faggioli
2015-07-24 16:18 ` Juergen Gross
2015-07-24 16:29 ` Konrad Rzeszutek Wilk
2015-07-24 16:39 ` Juergen Gross
2015-07-24 16:44 ` Boris Ostrovsky
2015-07-27 4:35 ` Juergen Gross
2015-07-27 10:43 ` George Dunlap
2015-07-27 10:54 ` Andrew Cooper
2015-07-27 11:13 ` Juergen Gross
2015-07-27 10:54 ` Juergen Gross
2015-07-27 11:11 ` George Dunlap
2015-07-27 12:01 ` Juergen Gross
2015-07-27 12:16 ` Tim Deegan
2015-07-27 13:23 ` Dario Faggioli
2015-07-27 14:02 ` Juergen Gross
2015-07-27 14:02 ` Dario Faggioli
2015-07-27 10:41 ` George Dunlap
2015-07-27 10:49 ` Andrew Cooper
2015-07-27 13:11 ` Dario Faggioli
2015-07-24 16:10 ` Juergen Gross
2015-07-24 16:40 ` Boris Ostrovsky
2015-07-24 16:48 ` Juergen Gross
2015-07-24 17:11 ` Boris Ostrovsky
2015-07-27 13:40 ` Dario Faggioli
2015-07-27 4:24 ` Juergen Gross
2015-07-27 14:09 ` Dario Faggioli
2015-07-27 14:34 ` Boris Ostrovsky
2015-07-27 14:43 ` Juergen Gross
2015-07-27 14:51 ` Boris Ostrovsky
2015-07-27 15:03 ` Juergen Gross
2015-07-27 14:47 ` Juergen Gross
2015-07-27 14:58 ` Dario Faggioli
2015-07-28 4:29 ` Juergen Gross
2015-07-28 15:11 ` Juergen Gross
2015-07-28 16:17 ` Dario Faggioli
2015-07-28 17:13 ` Dario Faggioli
2015-07-29 6:04 ` Juergen Gross
2015-07-29 7:09 ` Dario Faggioli
2015-07-29 7:44 ` Dario Faggioli
2015-07-24 16:05 ` Dario Faggioli
2015-07-28 10:05 ` Wei Liu
2015-07-28 15:17 ` Dario Faggioli
2015-07-24 20:27 ` Elena Ufimtseva
2015-07-22 14:50 ` Dario Faggioli
2015-07-22 15:32 ` Boris Ostrovsky
2015-07-22 15:49 ` Dario Faggioli
2015-07-22 18:10 ` Boris Ostrovsky
2015-07-23 7:25 ` Jan Beulich
2015-07-24 16:03 ` Boris Ostrovsky
2015-07-23 13:46 ` Dario Faggioli
2015-07-17 10:17 ` Andrew Cooper
2015-07-16 15:26 ` Wei Liu
2015-07-27 15:13 ` David Vrabel
2015-07-27 16:02 ` Dario Faggioli
2015-07-27 16:31 ` David Vrabel
2015-07-27 16:33 ` Andrew Cooper
2015-07-27 17:42 ` Dario Faggioli
2015-07-27 17:50 ` Konrad Rzeszutek Wilk
2015-07-27 23:19 ` Andrew Cooper
2015-07-28 3:52 ` Juergen Gross
2015-07-28 9:40 ` Andrew Cooper
2015-07-28 9:28 ` Dario Faggioli
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