Re: [Qemu-devel] [RFC V2 10/10] cpus: reclaim allocated vCPU objects

From: Bharata B Rao <bharata.rao@gmail.com>
To: Gu Zheng <guz.fnst@cn.fujitsu.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	tangchen@cn.fujitsu.com, isimatu.yasuaki@jp.fujitsu.com,
	Anshul Makkar <anshul.makkar@profitbricks.com>,
	chen.fan.fnst@cn.fujitsu.com, imammedo@redhat.com,
	"afaerber@suse.de" <afaerber@suse.de>
Subject: Re: [Qemu-devel] [RFC V2 10/10] cpus: reclaim allocated vCPU objects
Date: Fri, 12 Sep 2014 13:39:17 +0530	[thread overview]
Message-ID: <CAGZKiBoL7W2BXnOk5uGP4B_DpkzvA9vVftNzaMwSXrwFvMJfag@mail.gmail.com> (raw)
In-Reply-To: <54124B47.2050504@cn.fujitsu.com>

On Fri, Sep 12, 2014 at 6:54 AM, Gu Zheng <guz.fnst@cn.fujitsu.com> wrote:
> Is guest os enabled acpi cpu hotplug? What's the guest's cpu info?
> Please try latest QEMU, and any feedback is welcome.
>

Tried with latest QEMU git + your patchset and Fedora 20 guest, but
QEMU monitor still shows the removed CPU.

Guest kernel messages during hotplug:

[root@localhost cpu]# echo 1 > cpu8/online
[   72.936069] smpboot: Booting Node 0 Processor 8 APIC 0x8
[    0.003000] kvm-clock: cpu 8, msr 0:7ffc9201, secondary cpu clock
[   72.950003] TSC synchronization [CPU#0 -> CPU#8]:
[   72.950003] Measured 199886723309 cycles TSC warp between CPUs,
turning off TSC clock.
[   72.950003] tsc: Marking TSC unstable due to check_tsc_sync_source failed
[   72.972976] KVM setup async PF for cpu 8
[   72.973648] kvm-stealtime: cpu 8, msr 7d30df00
[   72.974415] Will online and init hotplugged CPU: 8
[   72.975307] microcode: CPU8 sig=0x663, pf=0x1, revision=0x1

Guest kernel messages during hotunplug:

[root@localhost cpu]# [   95.482172] Unregister pv shared memory for cpu 8
[   95.487169] smpboot: CPU 8 is now offline
[   95.488667] ACPI: Device does not support D3cold

Guest cpuinfo (showing for the last CPU only after adding and removing CPU 8)

processor    : 7
vendor_id    : GenuineIntel
cpu family    : 6
model        : 6
model name    : QEMU Virtual CPU version 2.1.50
stepping    : 3
microcode    : 0x1
cpu MHz        : 2899.998
cache size    : 4096 KB
fpu        : yes
fpu_exception    : yes
cpuid level    : 4
wp        : yes
flags        : fpu de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pse36 clflush mmx fxsr sse sse2 syscall nx lm rep_good nopl pni
cx16 x2apic popcnt hypervisor lahf_lm
bogomips    : 5799.99
clflush size    : 64
cache_alignment    : 64
address sizes    : 40 bits physical, 48 bits virtual
power management:

[root@localhost boot]# grep -ir hot config-3.11.10-301.fc20.x86_64
CONFIG_TICK_ONESHOT=y
# CONFIG_MEMORY_HOTPLUG is not set
CONFIG_HOTPLUG_CPU=y
# CONFIG_BOOTPARAM_HOTPLUG_CPU0 is not set
# CONFIG_DEBUG_HOTPLUG_CPU0 is not set
CONFIG_ARCH_ENABLE_MEMORY_HOTPLUG=y
CONFIG_ACPI_HOTPLUG_CPU=y
CONFIG_HOTPLUG_PCI_PCIE=y
CONFIG_HOTPLUG_PCI=y
CONFIG_HOTPLUG_PCI_ACPI=y
CONFIG_HOTPLUG_PCI_ACPI_IBM=m
# CONFIG_HOTPLUG_PCI_CPCI is not set
CONFIG_HOTPLUG_PCI_SHPC=m