Re: [Publicity] Xen Project Hypervisor 4.5 blog

[Sarah Conway <sconway@xxxxxxxxxxxxxxxxxxx>]

Hi Dario,

Thanks for this additional feedback. Regarding real-time scheduling, here is how it is described in the news release:Â

• Updates for automotive and embedded systems:ÂImproved multi-core, real-time scheduling support in Xen Project Hypervisor allows users to predict timing and performance of VM, laying the groundwork for Xen in embedded and automotive software stacks.

Should we more clearly identify it as an experimental feature?Â

Please advise.Â

Thanks,

On Wed, Jan 7, 2015 at 9:30 AM, Dario Faggioli <dario.faggioli@xxxxxxxxxx> wrote:

On Sun, 2015-01-04 at 16:53 -0600, Sarah Conway wrote:

> We also expanded support for:
>
>Â Â Â Â* vNUMA (The FOSS Outreach Program for Women sponsored this
>Â Â Â Â Âwork). Virtual NUMA allows Xen to expose to the guest the NUMA
>Â Â Â Â Âtopology (either based on the host or made-up) for the guest.
>
As Wei said, this is not something we could advertise as working yet,
although it really would be cool to at least mention the fact that
sensible progresses have been made on it...

>Â Â Â Â* Soft affinity for VCPUs (aka NUMA affinity) â In Xen 4.4 we
>    Âadded Automatic NUMA placement. In Xen 4.5 we build on that
>Â Â Â Â Âto allow VCPUs that go outside their NUMA silos â if it cannot
>Â Â Â Â Ârun inside the NUMA silos anymore (overcommit for example) â
>Â Â Â Â Âwe still want it to run â as opposed to not running.
>
This is inaccurate (and a bit hard to understand, at least to me). How
about:

"Soft affinity for vCPUs: Xen has [NUMA aware
scheduling](http://wiki.xen.org/wiki/Xen_on_NUMA_Machines) since 4.3. In
Xen 4.5, we build on that to make it more general, and useful on
non-NUMA systems too. In fact, it is now possible for the sysadmin to
define an arbitrary set of physical CPUs on which vCPUs prefer to run
on, and Xen will try as hard as possible to follow this indication"

>Â Â Â Â* Real Time Scheduler - improved multi-core support allows users
>    Âto predict timing and performance of VMs. Video at Youtube
>Â Â Â Â Âand presentation at Linux Foundation and blog.
>
This, IMO, is a really cool feature, and we must mention it, but let's
not forget it's experimental.

"Experimental support for Real-Time scheduling: a new, multicore
enabled, real-time scheduler, called RTDS ([link to video?]), is part of
Xen 4.5 as an experimental feature. Virtualization will soon become the
norm rather than the exception in automotive, avionics, mobile and
multimedia, and other fields where predictability and high-end real-time
support are critical. Xen wants to play a big role in this, and this new
scheduler will allow for such. That is way we introduced it in 4.5, even
if it is still under development"

Of course, feel free to rephrase in proper English, shorten, expand,
whatever. :-)

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)

--

Sarah Conway

PR Manager

The Linux Foundation
sconway@xxxxxxxxxxxxxxxxxxx

(978) 578-5300 ÂCell

Skype: Âsarah.k.conway

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