[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-ppc] [PATCH 6/8] spapr: init CPUState->cpu_index with index re
|
From: |
Bharata B Rao |
|
Subject: |
Re: [Qemu-ppc] [PATCH 6/8] spapr: init CPUState->cpu_index with index relative to core-id |
|
Date: |
Fri, 22 Jul 2016 11:40:03 +0530 |
|
User-agent: |
Mutt/1.6.1 (2016-04-27) |
On Fri, Jul 22, 2016 at 01:23:01PM +1000, David Gibson wrote:
> On Thu, Jul 21, 2016 at 05:54:37PM +0200, Igor Mammedov wrote:
> > It will enshure that cpu_index for a given cpu stays the same
> > regardless of the order cpus has been created/deleted and so
> > it would be possible to migrate QEMU instance with out of order
> > created CPU.
> >
> > Signed-off-by: Igor Mammedov <address@hidden>
>
> So, this isn't quite right (it wasn't right in my version either).
>
> The problem occurs when smp_threads < kvmppc_smt_threads(). That is,
> when the requested threads-per-core is less than the hardware's
> maximum number of threads-per-core.
>
> The core-id values are assigned essentially as i *
> kvmppc_smt_threads(), meaning the patch below will leave gaps in the
> cpu_index values and the last ones will exceed max_cpus, causing other
> problems.
This would lead to hotplug failures as cpu_dt_id is still being
derived from non-contiguous cpu_index resulting in wrong enumeration
of CPU nodes in DT.
For -smp 8,threads=4 we see the following CPU nodes in DT
PowerPC,address@hidden PowerPC,address@hidden
which otherwise should have been
PowerPC,address@hidden PowerPC,address@hidden
The problem manifests as drmgr failure.
Greg's patchset that moved cpu_dt_id setting to machine code and that
derived cpu_dt_id from core-id for sPAPR would be needed to fix this I guess.
Regards,
Bharata.
- Re: [Qemu-ppc] [PATCH 2/8] exec: don't use cpu_index to detect if cpu_exec_init()'s been called for cpu, (continued)
[Qemu-ppc] [PATCH 1/8] exec: reduce CONFIG_USER_ONLY ifdeffenery, Igor Mammedov, 2016/07/21
[Qemu-ppc] [PATCH 3/8] exec: set cpu_index only if it's been explictly set, Igor Mammedov, 2016/07/21
[Qemu-ppc] [PATCH 5/8] pc: init CPUState->cpu_index with index in possible_cpus[], Igor Mammedov, 2016/07/21
[Qemu-ppc] [PATCH 6/8] spapr: init CPUState->cpu_index with index relative to core-id, Igor Mammedov, 2016/07/21
Re: [Qemu-ppc] [Qemu-devel] [PATCH 6/8] spapr: init CPUState->cpu_index with index relative to core-id, David Gibson, 2016/07/26
[Qemu-ppc] [PATCH 4/8] qdev: fix object reference leak in case device.realize() fails, Igor Mammedov, 2016/07/21
[Qemu-ppc] [PATCH 7/8] Revert "pc: Enforce adding CPUs contiguously and removing them in opposite order", Igor Mammedov, 2016/07/21
[Qemu-ppc] [PATCH 8/8] Revert "spapr: Ensure CPU cores are added contiguously and removed in LIFO order", Igor Mammedov, 2016/07/21
Re: [Qemu-ppc] [PATCH 0/8] Fix migration issues with arbitrary cpu-hot(un)plug, Michael S. Tsirkin, 2016/07/21