On Thu, Sep 10, 2020 at 01:35:32PM +0200, Laurent Dufour wrote:
> That points has been raised by David, quoting him here:
>
> > IIRC, ACPI can hotadd memory while SCHEDULING, this patch would break that.
> >
> > Ccing Oscar, I think he mentioned recently that this is the case with ACPI.
>
> Oscar told that he need to investigate further on that.
I think my reply got lost.
We can see acpi hotplugs during SYSTEM_SCHEDULING:
$QEMU -enable-kvm -machine pc -smp 4,sockets=4,cores=1,threads=1 -cpu host -monitor pty \
-m size=$MEM,slots=255,maxmem=4294967296k \
-numa node,nodeid=0,cpus=0-3,mem=512 -numa node,nodeid=1,mem=512 \
-object memory-backend-ram,id=memdimm0,size=134217728 -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0 \
-object memory-backend-ram,id=memdimm1,size=134217728 -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1 \
-object memory-backend-ram,id=memdimm2,size=134217728 -device pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2 \
-object memory-backend-ram,id=memdimm3,size=134217728 -device pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3 \
-object memory-backend-ram,id=memdimm4,size=134217728 -device pc-dimm,node=1,memdev=memdimm4,id=dimm4,slot=4 \
-object memory-backend-ram,id=memdimm5,size=134217728 -device pc-dimm,node=1,memdev=memdimm5,id=dimm5,slot=5 \
-object memory-backend-ram,id=memdimm6,size=134217728 -device pc-dimm,node=1,memdev=memdimm6,id=dimm6,slot=6 \
kernel: [ 0.753643] __add_memory: nid: 0 start: 0100000000 - 0108000000 (size: 134217728)
kernel: [ 0.756950] register_mem_sect_under_node: system_state= 1
kernel: [ 0.760811] register_mem_sect_under_node+0x4f/0x230
kernel: [ 0.760811] walk_memory_blocks+0x80/0xc0
kernel: [ 0.760811] link_mem_sections+0x32/0x40
kernel: [ 0.760811] add_memory_resource+0x148/0x250
kernel: [ 0.760811] __add_memory+0x5b/0x90
kernel: [ 0.760811] acpi_memory_device_add+0x130/0x300
kernel: [ 0.760811] acpi_bus_attach+0x13c/0x1c0
kernel: [ 0.760811] acpi_bus_attach+0x60/0x1c0
kernel: [ 0.760811] acpi_bus_scan+0x33/0x70
kernel: [ 0.760811] acpi_scan_init+0xea/0x21b
kernel: [ 0.760811] acpi_init+0x2f1/0x33c
kernel: [ 0.760811] do_one_initcall+0x46/0x1f4
--
Oscar Salvador
SUSE L3
Le 10/09/2020 à 14:03, Oscar Salvador a écrit :
> On Thu, Sep 10, 2020 at 01:35:32PM +0200, Laurent Dufour wrote:
>
>> That points has been raised by David, quoting him here:
>>
>>> IIRC, ACPI can hotadd memory while SCHEDULING, this patch would break that.
>>>
>>> Ccing Oscar, I think he mentioned recently that this is the case with ACPI.
>>
>> Oscar told that he need to investigate further on that.
>
> I think my reply got lost.
>
> We can see acpi hotplugs during SYSTEM_SCHEDULING:
>
> $QEMU -enable-kvm -machine pc -smp 4,sockets=4,cores=1,threads=1 -cpu host -monitor pty \
> -m size=$MEM,slots=255,maxmem=4294967296k \
> -numa node,nodeid=0,cpus=0-3,mem=512 -numa node,nodeid=1,mem=512 \
> -object memory-backend-ram,id=memdimm0,size=134217728 -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0 \
> -object memory-backend-ram,id=memdimm1,size=134217728 -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1 \
> -object memory-backend-ram,id=memdimm2,size=134217728 -device pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2 \
> -object memory-backend-ram,id=memdimm3,size=134217728 -device pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3 \
> -object memory-backend-ram,id=memdimm4,size=134217728 -device pc-dimm,node=1,memdev=memdimm4,id=dimm4,slot=4 \
> -object memory-backend-ram,id=memdimm5,size=134217728 -device pc-dimm,node=1,memdev=memdimm5,id=dimm5,slot=5 \
> -object memory-backend-ram,id=memdimm6,size=134217728 -device pc-dimm,node=1,memdev=memdimm6,id=dimm6,slot=6 \
>
> kernel: [ 0.753643] __add_memory: nid: 0 start: 0100000000 - 0108000000 (size: 134217728)
> kernel: [ 0.756950] register_mem_sect_under_node: system_state= 1
>
> kernel: [ 0.760811] register_mem_sect_under_node+0x4f/0x230
> kernel: [ 0.760811] walk_memory_blocks+0x80/0xc0
> kernel: [ 0.760811] link_mem_sections+0x32/0x40
> kernel: [ 0.760811] add_memory_resource+0x148/0x250
> kernel: [ 0.760811] __add_memory+0x5b/0x90
> kernel: [ 0.760811] acpi_memory_device_add+0x130/0x300
> kernel: [ 0.760811] acpi_bus_attach+0x13c/0x1c0
> kernel: [ 0.760811] acpi_bus_attach+0x60/0x1c0
> kernel: [ 0.760811] acpi_bus_scan+0x33/0x70
> kernel: [ 0.760811] acpi_scan_init+0xea/0x21b
> kernel: [ 0.760811] acpi_init+0x2f1/0x33c
> kernel: [ 0.760811] do_one_initcall+0x46/0x1f4
Thanks Oscar!
On Thu 10-09-20 14:03:48, Oscar Salvador wrote:
> On Thu, Sep 10, 2020 at 01:35:32PM +0200, Laurent Dufour wrote:
>
> > That points has been raised by David, quoting him here:
> >
> > > IIRC, ACPI can hotadd memory while SCHEDULING, this patch would break that.
> > >
> > > Ccing Oscar, I think he mentioned recently that this is the case with ACPI.
> >
> > Oscar told that he need to investigate further on that.
>
> I think my reply got lost.
>
> We can see acpi hotplugs during SYSTEM_SCHEDULING:
>
> $QEMU -enable-kvm -machine pc -smp 4,sockets=4,cores=1,threads=1 -cpu host -monitor pty \
> -m size=$MEM,slots=255,maxmem=4294967296k \
> -numa node,nodeid=0,cpus=0-3,mem=512 -numa node,nodeid=1,mem=512 \
> -object memory-backend-ram,id=memdimm0,size=134217728 -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0 \
> -object memory-backend-ram,id=memdimm1,size=134217728 -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1 \
> -object memory-backend-ram,id=memdimm2,size=134217728 -device pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2 \
> -object memory-backend-ram,id=memdimm3,size=134217728 -device pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3 \
> -object memory-backend-ram,id=memdimm4,size=134217728 -device pc-dimm,node=1,memdev=memdimm4,id=dimm4,slot=4 \
> -object memory-backend-ram,id=memdimm5,size=134217728 -device pc-dimm,node=1,memdev=memdimm5,id=dimm5,slot=5 \
> -object memory-backend-ram,id=memdimm6,size=134217728 -device pc-dimm,node=1,memdev=memdimm6,id=dimm6,slot=6 \
>
> kernel: [ 0.753643] __add_memory: nid: 0 start: 0100000000 - 0108000000 (size: 134217728)
> kernel: [ 0.756950] register_mem_sect_under_node: system_state= 1
>
> kernel: [ 0.760811] register_mem_sect_under_node+0x4f/0x230
> kernel: [ 0.760811] walk_memory_blocks+0x80/0xc0
> kernel: [ 0.760811] link_mem_sections+0x32/0x40
> kernel: [ 0.760811] add_memory_resource+0x148/0x250
> kernel: [ 0.760811] __add_memory+0x5b/0x90
> kernel: [ 0.760811] acpi_memory_device_add+0x130/0x300
> kernel: [ 0.760811] acpi_bus_attach+0x13c/0x1c0
> kernel: [ 0.760811] acpi_bus_attach+0x60/0x1c0
> kernel: [ 0.760811] acpi_bus_scan+0x33/0x70
> kernel: [ 0.760811] acpi_scan_init+0xea/0x21b
> kernel: [ 0.760811] acpi_init+0x2f1/0x33c
> kernel: [ 0.760811] do_one_initcall+0x46/0x1f4
Is there any actual usecase for a configuration like this? What is the
point to statically define additional memory like this when the same can
be achieved on the same command line?
--
Michal Hocko
SUSE Labs
On 10.09.20 14:47, Michal Hocko wrote:
> On Thu 10-09-20 14:03:48, Oscar Salvador wrote:
>> On Thu, Sep 10, 2020 at 01:35:32PM +0200, Laurent Dufour wrote:
>>
>>> That points has been raised by David, quoting him here:
>>>
>>>> IIRC, ACPI can hotadd memory while SCHEDULING, this patch would break that.
>>>>
>>>> Ccing Oscar, I think he mentioned recently that this is the case with ACPI.
>>>
>>> Oscar told that he need to investigate further on that.
>>
>> I think my reply got lost.
>>
>> We can see acpi hotplugs during SYSTEM_SCHEDULING:
>>
>> $QEMU -enable-kvm -machine pc -smp 4,sockets=4,cores=1,threads=1 -cpu host -monitor pty \
>> -m size=$MEM,slots=255,maxmem=4294967296k \
>> -numa node,nodeid=0,cpus=0-3,mem=512 -numa node,nodeid=1,mem=512 \
>> -object memory-backend-ram,id=memdimm0,size=134217728 -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0 \
>> -object memory-backend-ram,id=memdimm1,size=134217728 -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1 \
>> -object memory-backend-ram,id=memdimm2,size=134217728 -device pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2 \
>> -object memory-backend-ram,id=memdimm3,size=134217728 -device pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3 \
>> -object memory-backend-ram,id=memdimm4,size=134217728 -device pc-dimm,node=1,memdev=memdimm4,id=dimm4,slot=4 \
>> -object memory-backend-ram,id=memdimm5,size=134217728 -device pc-dimm,node=1,memdev=memdimm5,id=dimm5,slot=5 \
>> -object memory-backend-ram,id=memdimm6,size=134217728 -device pc-dimm,node=1,memdev=memdimm6,id=dimm6,slot=6 \
>>
>> kernel: [ 0.753643] __add_memory: nid: 0 start: 0100000000 - 0108000000 (size: 134217728)
>> kernel: [ 0.756950] register_mem_sect_under_node: system_state= 1
>>
>> kernel: [ 0.760811] register_mem_sect_under_node+0x4f/0x230
>> kernel: [ 0.760811] walk_memory_blocks+0x80/0xc0
>> kernel: [ 0.760811] link_mem_sections+0x32/0x40
>> kernel: [ 0.760811] add_memory_resource+0x148/0x250
>> kernel: [ 0.760811] __add_memory+0x5b/0x90
>> kernel: [ 0.760811] acpi_memory_device_add+0x130/0x300
>> kernel: [ 0.760811] acpi_bus_attach+0x13c/0x1c0
>> kernel: [ 0.760811] acpi_bus_attach+0x60/0x1c0
>> kernel: [ 0.760811] acpi_bus_scan+0x33/0x70
>> kernel: [ 0.760811] acpi_scan_init+0xea/0x21b
>> kernel: [ 0.760811] acpi_init+0x2f1/0x33c
>> kernel: [ 0.760811] do_one_initcall+0x46/0x1f4
>
> Is there any actual usecase for a configuration like this? What is the
> point to statically define additional memory like this when the same can
> be achieved on the same command line?
You can online it movable right away to unplug later.
Also, under QEMU, just do a reboot with hotplugged memory and you're in
the very same situation.
--
Thanks,
David / dhildenb