On Mon, 2015-01-26 at 04:25 +0100, Alexandre DERUMIER wrote:
> >>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.
>
>
Now in the guest, VCPUs are assigned round-robin.
But in qemu, vcpus' property 'numa_node' was assigned the default
value 0.
We have made a patchset to solve this successfully.
But we plan to send the patchset to the community later.
Regards,
Zhu
> ----- 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
> [...]
>
