On 2016/12/2 10:38, Scott Branden wrote:
> Hi Xishi,
>
> Thanks for the reply - please see comments below.
>
> On 16-12-01 05:49 PM, Xishi Qiu wrote:
>> On 2016/12/2 8:19, Scott Branden wrote:
>>
>>> This patchset is sent for comment to add memory hotplug support for ARM64
>>> based platforms. It follows hotplug code added for other architectures
>>> in the linux kernel.
>>>
>>> I tried testing the memory hotplug feature following documentation from
>>> Documentation/memory-hotplug.txt. I don't think it is working as expected
>>> - see below:
>>>
>>> To add memory to the system I did the following:
>>> echo 0x400000000 > /sys/devices/system/memory/probe
>>>
>>> The memory is displayed as system ram:
>>> cat /proc/iomem:
>>> 74000000-77ffffff : System RAM
>>> 74080000-748dffff : Kernel code
>>> 74950000-749d2fff : Kernel data
>>> 400000000-43fffffff : System RAM
>>>
>>> But does not seem to be added to the kernel memory.
>>> /proc/meminfo did not change.
>>>
>>> What else needs to be done so the memory is added to the kernel memory
>>> pool for normal allocation?
>>>
>>
>> Hi Scott,
>>
>> Do you mean it still don't support hod-add after apply this patchset?
>
> After applying the patch it appears to partially support hot-add. Please let
> me know if you think it is working as expected?
>
> The memory probe functions in that the memory is registered with the system
> and shows up in /proc/iomem. But, the memory is not available in
> /proc/meminfo. Do you think something else needs to be adjusted for ARM64 to
> hotadd the memory
>
> I just found another clue:
> under /sys/devices/system/memory I only see one memory entry (before or after
> I try to hotadd additional memory).
>
> /sys/devices/system/memory # ls
> auto_online_blocks memory0 uevent
> block_size_bytes probe
>
> In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 30
> to 28 and recompile I get the following:
> /sys/devices/system/memory # ls
> auto_online_blocks memory7 uevent
> block_size_bytes probe
>
>
> In arch/arm64/include/asm/sparsemem.h if I change SECTION_SIZE_BITS from 30
> to 27 and recompile I get the following:
> /sys/devices/system/memory # ls
> auto_online_blocks memory14 uevent
> block_size_bytes probe
>
> If looks to me like something is not working properly in the ARM64
> implementation. I should expect to see multiple memoryX entries under
> /sys/devices/system/memory?
>
Hi Scott,
1. Do you enable the following configs?
CONFIG_SPARSEMEM
MEMORY_HOTPLUG
CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
2. I find you missed create mapping in arch_add_memory(), and x86 has it.
3. We will add memblock first, so pfn_valid() maybe always return true(in the
following function), and this will lead __add_section() failed. Please check
it.
int pfn_valid(unsigned long pfn)
{
return (pfn & PFN_MASK) == pfn && memblock_is_memory(pfn << PAGE_SHIFT);
}
add_memory
add_memory_resource
memblock_add_node
arch_add_memory
__add_pages
__add_section
pfn_valid
Thanks,
Xishi Qiu
>
>
>>
>> Thanks,
>> Xishi Qiu
>>
>>> Scott Branden (2):
>>> arm64: memory-hotplug: Add MEMORY_HOTPLUG, MEMORY_HOTREMOVE,
>>> MEMORY_PROBE
>>> arm64: defconfig: enable MEMORY_HOTPLUG config options
>>>
>>> arch/arm64/Kconfig | 10 ++++++++++
>>> arch/arm64/configs/defconfig | 3 +++
>>> arch/arm64/mm/init.c | 42
>>> ++++++++++++++++++++++++++++++++++++++++++
>>> 3 files changed, 55 insertions(+)
>>>
>>
>>
>>
>
> .
>
