[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC PATCH v1 00/13] CPU and Memory hotplug for PowerPC
From: |
Andreas Färber |
Subject: |
Re: [Qemu-devel] [RFC PATCH v1 00/13] CPU and Memory hotplug for PowerPC guests |
Date: |
Thu, 29 Jan 2015 18:46:30 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 |
Hi,
Am 08.01.2015 um 07:10 schrieb Bharata B Rao:
> This patchset enables CPU and memory hotplug support for PowerPC guests.
>
> Changes in this patchset (v1):
>
> - Based on top of Michael Roth's tree
> (https://github.com/mdroth/qemu/commits/spapr-hotplug-core) which serves
> as base for his PCI hotplug patches too.
> - Switched to device_add/del semantics instead of cpu-add.
Please don't forget to CC me on this. As previously discussed with Jason
and Christian for s390x, there's certain topology modeling questions
still unsolved for device-based QOM CPU hot-plug. I have an RFC in the
works (again) that hopefully gets us a step closer.
> - Supporting CPU hot unplug now.
> - Added patches to enable memory hotplug.
> - Added ibm,dynamic-reconfiguration-memory support which is needed for
> memory hotplug.
>
> v0 - http://lists.nongnu.org/archive/html/qemu-devel/2014-09/msg00752.html
>
> CPU hotplug
> -----------
> - Works with BE guest, has issues with LE guest. Has been tested on BE host
> only.
> - Adding a core (and all its threads) in response to device_add command.
> Similarly removing a core via device_del will remove all the threads.
Earlier discussions concluded that hot-plug needs to happen on a socket
level, not core. If you're assuming the socket to have one core (as we
were planning for s390x), that doesn't make much of a difference
number-wise, but it does in modeling terms. Think what you can
physically plug onto the mainboard, that's the granularity that
realized=true/false is going to operate on. A virtual socket may well
correspond to a thread on some socket/node of the host, but you cannot
add threads to a core or cores to a chip at runtime.
On x86 this may become a functional limitation of what is possible
through cpu-add, so better avoid that mistake for ppc from the start.
Regards,
Andreas
> - Using Gu Zheng's "reclaim vCPU objects" patch to remove and reuse
> the vCPU objects after CPUs removal.
> (Gu Zheng's original patch:
> http://lists.gnu.org/archive/html/qemu-devel/2014-12/msg01829.html)
[snip]
--
SUSE Linux GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Felix Imendörffer, Jane Smithard, Jennifer Guild, Dilip Upmanyu,
Graham Norton; HRB 21284 (AG Nürnberg)
signature.asc
Description: OpenPGP digital signature
[Qemu-devel] [RFC PATCH v1 10/13] cpus, spapr: reclaim allocated vCPU objects, Bharata B Rao, 2015/01/08
Re: [Qemu-devel] [RFC PATCH v1 00/13] CPU and Memory hotplug for PowerPC guests,
Andreas Färber <=
Re: [Qemu-devel] [RFC PATCH v1 00/13] CPU and Memory hotplug for PowerPC guests, Tyrel Datwyler, 2015/01/29