>>2)when numa is used, the hotplugged cpu is always on numa node 0
>>(cpu_add or device_add cpu)
About this, it seem to be a display bug in "info numa",
cpu is correctly assigned to numa node1 in the guest.
----- Mail original -----
De: "aderumier" <aderum...@odiso.com>
À: "Zhu Guihua" <zhugh.f...@cn.fujitsu.com>
Cc: "qemu-devel" <qemu-devel@nongnu.org>, tangc...@cn.fujitsu.com, "guz fnst"
<guz.f...@cn.fujitsu.com>, "isimatu yasuaki" <isimatu.yasu...@jp.fujitsu.com>,
"Anshul Makkar" <anshul.mak...@profitbricks.com>, "chen fan fnst"
<chen.fan.f...@cn.fujitsu.com>, "Igor Mammedov" <imamm...@redhat.com>,
"afaerber" <afaer...@suse.de>
Envoyé: Lundi 26 Janvier 2015 04:19:52
Objet: Re: [Qemu-devel] [PATCH v2 00/11] cpu: add i386 cpu hot remove support
Thanks for your reply.
2 others things:
1)
on cpu unplug, I see that the cpu is correctly removed from my linux guest but
not from qemu
starting with a guest with 3cpus:
guest: #ls -lah /sys/devices/system/ |grep cpu
drwxr-xr-x 6 root root 0 Jan 25 22:16 cpu0
drwxr-xr-x 6 root root 0 Jan 25 22:16 cpu1
drwxr-xr-x 6 root root 0 Jan 25 22:16 cpu2
hmp: # info cpus
* CPU #0: pc=0xffffffff81057022 (halted) thread_id=24972
CPU #1: pc=0xffffffff81057022 (halted) thread_id=24973
CPU #2: pc=0xffffffff81048bc1 (halted) thread_id=25102
then unplug cpu2
hmp : device_del cpu2
guest:
dmesg:
[ 176.219754] Unregister pv shared memory for cpu 2
[ 176.278881] smpboot: CPU 2 is now offline
#ls -lah /sys/devices/system/ |grep cpu
drwxr-xr-x 6 root root 0 Jan 25 22:16 cpu0
drwxr-xr-x 6 root root 0 Jan 25 22:16 cpu1
hmp: # info cpus
* CPU #0: pc=0xffffffff81057022 (halted) thread_id=24972
CPU #1: pc=0xffffffff81057022 (halted) thread_id=24973
CPU #2: pc=0xffffffff81048bc1 (halted) thread_id=25102
2)when numa is used, the hotplugged cpu is always on numa node 0
(cpu_add or device_add cpu)
starting a guest, with 2 sockets,1 cores
-smp 2,sockets=2,cores=1,maxcpus=2
-object memory-backend-ram,size=256M,id=ram-node0 -numa
node,nodeid=0,cpus=0,memdev=ram-node0
-object memory-backend-ram,size=256M,id=ram-node1 -numa
node,nodeid=1,cpus=1,memdev=ram-node1
hmp:
# info numa
2 nodes
node 0 cpus: 0
node 0 size: 256 MB
node 1 cpus: 1
node 1 size: 256 MB
ok
now
starting with same topology, but with 1cpu at start
-smp 2,sockets=2,cores=1,maxcpus=2
-object memory-backend-ram,size=256M,id=ram-node0 -numa
node,nodeid=0,cpus=0,memdev=ram-node0
-object memory-backend-ram,size=256M,id=ram-node1 -numa
node,nodeid=1,cpus=1,memdev=ram-node1
# info numa
2 nodes
node 0 cpus: 0
node 0 size: 256 MB
node 1 cpus:
node 1 size: 256 MB
hotpluging a cpu
# device_add kvm64-x86_64-cpu,apic-id=1,id=cpu1
# info numa
2 nodes
node 0 cpus: 0 1
node 0 size: 256 MB
node 1 cpus:
node 1 size: 256 MB
cpu1 should be on node1, not node0.
Regards,
Alexandre
----- Mail original -----
De: "Zhu Guihua" <zhugh.f...@cn.fujitsu.com>
À: "aderumier" <aderum...@odiso.com>
Cc: "qemu-devel" <qemu-devel@nongnu.org>, tangc...@cn.fujitsu.com, "guz fnst"
<guz.f...@cn.fujitsu.com>, "isimatu yasuaki" <isimatu.yasu...@jp.fujitsu.com>,
"Anshul Makkar" <anshul.mak...@profitbricks.com>, "chen fan fnst"
<chen.fan.f...@cn.fujitsu.com>, "Igor Mammedov" <imamm...@redhat.com>,
"afaerber" <afaer...@suse.de>
Envoyé: Lundi 26 Janvier 2015 03:01:48
Objet: Re: [Qemu-devel] [PATCH v2 00/11] cpu: add i386 cpu hot remove support
On Fri, 2015-01-23 at 11:24 +0100, Alexandre DERUMIER wrote:
> Hello,
>
> I'm currently testing the new cpu unplug features,
> Works fine here with debian guests and kernel 3.14.
>
Thanks for your test.
> But I have notice some small potential bugs, but I'm not sure I'm doing it
> right.
>
> 1)first, to unplug cpu, we need an id for cpu
>
Yes, if you want to unplug cpu, you must have an id for cpu.
> The problem is that the current qemu command line
> -smp 1,sockets=2,cores=1,maxcpus=2
>
> for example, will create 1 cpu on apic-id 0 without any id, so we can't
> unplug it.
>
>
> So, I have tried with
>
> -smp 1,sockets=2,cores=1,maxcpus=2 -device kvm64-x86_64-cpu,apic-id=0,id=cpu0
>
> But this give me an error:
> "-device kvm64-x86_64-cpu,apic-id=0,id=cpu0: CPU with APIC ID 0 exists"
>
APIC ID 0 was used by the cpu of '-smp 1'.
So you should use apic-id=1
> (also try to set -smp 0, but it's not working).
>
>
>
> 2) second problem, if I start with
> -smp 1,sockets=2,cores=1,maxcpus=2
>
> then hmp:
> device_add kvm64-x86_64-cpu,apic-id=1,id=cpu1
>
> then hmp : device_del cpu1
>
> Got an error:"
> This is the last cpu, should not be removed!"
>
>
Oh, it's our problem, thanks for your pointing out.
I will fix it in next version.
Regards,
Zhu
>
> This is coming from
> [PATCH 06/12] pc: add cpu hot unplug request callback support
> + if (smp_cpus == 1) {
> + error_setg(&local_err,
> + "This is the last cpu, should not be removed!");
> + goto out;
> + }
>
>
>
> So, the only way unplug is working for me, is to start with -smp 2 minimum
> -smp 2,sockets=2,cores=1,maxcpus=4
>
> Then I can hotplug|unplug cpuid >= 2
>
>
>
> Regards,
>
> Alexandre Derumier
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