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== Comment: #0 - Satheesh Rajendran <sathe...@in.ibm.com> - 2017-02-28 06:00:53
==
---Problem Description---
Guest does not reflect all the cpus hotplugged,
Holpug vcpus using setvcpu with initial less number of cpus(1) to a greater
cpus(~256), though
setvcpu(libvirt) returns no error, guest does not reflect all cpus inside.
Contact Information = sathe...@in.ibm.com
---uname output---
Linux ltc-test-ci1 4.10.0-9-generic #11-Ubuntu SMP Mon Feb 20 13:45:11 UTC 2017
ppc64le ppc64le ppc64le GNU/Linux
Machine Type = power 8 ppc64le
---Debugger---
A debugger is not configured
---Steps to Reproduce---
1. Start the guest(Ubuntu 17.04) with 1 current vcpu and 255 maxvcpus
...
<vcpu placement='static' current='1'>255</vcpu>
...
<cpu>
<topology sockets='1' cores='255' threads='1'/>
</cpu>
....
# lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 1
On-line CPU(s) list: 0
Thread(s) per core: 1
Core(s) per socket: 1
Socket(s): 1
NUMA node(s): 1
Model: 2.1 (pvr 004b 0201)
Model name: POWER8E (raw), altivec supported
Hypervisor vendor: KVM
Virtualization type: para
L1d cache: 64K
L1i cache: 32K
NUMA node0 CPU(s): 0
2.# time virsh setvcpus virt-tests-vm1 255 --live --config
real 0m4.460s
user 0m0.012s
sys 0m0.000s
root@ltc-test-ci1:/var/lib/libvirt/images/workspace/runAvocadoFVTTest/avocado-fvt-wrapper#
echo $?
0
3. Check inside the guest after some time (10-15 mins) (
dmesg of guest shows all the RTAS(255) events,but the guest showed only 90
vcpus(it consistent around ~ 100 always).
root@ubuntu:~# lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 97
On-line CPU(s) list: 0-96
Thread(s) per core: 1
Core(s) per socket: 97
Socket(s): 1
NUMA node(s): 1
Model: 2.1 (pvr 004b 0201)
Model name: POWER8E (raw), altivec supported
Hypervisor vendor: KVM
Virtualization type: para
L1d cache: 64K
L1i cache: 32K
NUMA node0 CPU(s): 0-96
root@ubuntu:~# tail /proc/cpuinfo
processor : 96
cpu : POWER8E (raw), altivec supported
clock : 3425.000000MHz
revision : 2.1 (pvr 004b 0201)
timebase : 512000000
platform : pSeries
model : IBM pSeries (emulated by qemu)
machine : CHRP IBM pSeries (emulated by qemu)
Userspace tool common name: libvirt, qemu
The userspace tool has the following bit modes: both
Userspace rpm: qemu-kvm 1:2.8+dfsg-
2ubuntu1 ppc64el,ii libvirt-bin
2.5.0-3ubuntu2 ppc64el
Userspace tool obtained from project website: na
Guest Details:
#cat /etc/os-release |grep VERSION=
VERSION="17.04 (Zesty Zapus)"
# uname -a
Linux ubuntu 4.10.0-8-generic #10-Ubuntu SMP Mon Feb 13 14:00:06 UTC 2017
ppc64le ppc64le ppc64le GNU/Linux
root@ubuntu:~# dpkg -l |grep rtas
ii librtas-dev 2.0.0-2
ppc64el userspace RTAS library development files
ii librtas2 2.0.0-2
ppc64el userspace RTAS library
ii librtasevent-dev 2.0.0-2
ppc64el RTAS events library development files
ii librtasevent2 2.0.0-2
ppc64el RTAS events library
ii ppc64-diag 2.7.1-6
ppc64el Platform error log analysis tool and rtas_errd daemon
*Additional Instructions for sathe...@in.ibm.com:
-Post a private note with access information to the machine that the bug is
occuring on.
-Attach ltrace and strace of userspace application.
== Comment: #9 - BHARATA BHASKER RAO <bharata....@in.ibm.com> - 2017-03-03
04:32:14 ==
When a large number of hotplug requests are generated too quickly, guest will
miss the handling of a few RTAS events due to buffer overrun. Because of this,
guest will not see all the hotplugged CPUs. This was raised earlier in bz
142499 with the following resolution:
- We need in-kernel CPU hotplug feature in the guest for this to work.
- Until in-kernel CPU hotplug is available in the guest kernel, user should be
careful not to overload the guest with so many successive hotplug requests.
I reproduced the problem with ubuntu-1704 guest (with default kernel)
and was able to get over the problem with a self-compiled guest kernel
from latest linux git that has in-kernel CPU hotplug.
bharata@ubuntu-1704:~$ uname -a
Linux ubuntu-1704 4.10.0+ #1 SMP Fri Mar 3 15:42:46 IST 2017 ppc64le ppc64le
ppc64le GNU/Linux
bharata@ubuntu-1704:~$ lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 255
On-line CPU(s) list: 0-254
Thread(s) per core: 1
Core(s) per socket: 1
Socket(s): 255
NUMA node(s): 1
Model: 2.0 (pvr 004d 0200)
Model name: POWER8 (raw), altivec supported
Hypervisor vendor: KVM
Virtualization type: para
L1d cache: 64K
L1i cache: 32K
NUMA node0 CPU(s): 0-254
== Comment: #10 - BHARATA BHASKER RAO <bharata....@in.ibm.com> - 2017-03-06
02:28:42 ==
commit 3dbbaf200f532e01e56168b8339f2981f2cb1d67
Author: Michael Roth <mdr...@linux.vnet.ibm.com>
Date: Mon Feb 20 19:12:18 2017 -0600
powerpc/pseries: Advertise Hot Plug Event support to firmware
With the inclusion of commit 333f7b76865b ("powerpc/pseries: Implement
indexed-count hotplug memory add") and commit 753843471cbb
("powerpc/pseries: Implement indexed-count hotplug memory remove"), we
now have complete handling of the RTAS hotplug event format as described
by PAPR via ACR "PAPR Changes for Hotplug RTAS Events".
This capability is indicated by byte 6, bit 2 (5 in IBM numbering) of
architecture option vector 5, and allows for greater control over
cpu/memory/pci hot plug/unplug operations.
Existing pseries kernels will utilize this capability based on the
existence of the /event-sources/hot-plug-events DT property, so we
only need to advertise it via CAS and do not need a corresponding
FW_FEATURE_* value to test for.
Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
$ git tag --contains 3dbbaf200
v4.11-rc1
$
Commit 3dbbaf200 is available upstream in kernel v4.11-rc1 onwards, thus
missing from 1704 kernel. This commit is needed for memory unplug support.
** Affects: linux (Ubuntu)
Importance: Undecided
Assignee: Taco Screen team (taco-screen-team)
Status: New
** Tags: architecture-ppc64le bugnameltc-152070 severity-critical
targetmilestone-inin1704
--
Ubuntu 17.04: Guest does not reflect all the cpus hotplugged
https://bugs.launchpad.net/bugs/1670315
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