Hi Vishal,
On 07/12/2023 12:36, Vishal Verma wrote:
> +
> +What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory
> +Date: October, 2023
> +KernelVersion: v6.8
> +Contact: nvd...@lists.linux.dev
> +Description:
> + (RW) Control the memmap_on_memory setting if the dax device
> + were to be hotplugged as system memory. This determines whether
> + the 'altmap' for the hotplugged memory will be placed on the
> + device being hotplugged (memmap_on+memory=1) or if it will be
s/memmap_on+memory=1/memmap_on_memory=1
I have a question here
What relationship about memmap_on_memory and 'ndctl-create-namespace -M' option
which
specifies where is the vmemmap backed memory.
I'm confused that memmap_on_memory=1 and '-M dev' are the same for nvdimm
devdax mode ?
ndctl-create-namespace
...
-M, --map=
A pmem namespace in "fsdax" or "devdax" mode requires allocation of
per-page metadata. The allocation
can be drawn from either:
• "mem": typical system memory
• "dev": persistent memory reserved from the namespace :: Given
relative capacities of "Persistent
Memory" to "System RAM" the allocation defaults to reserving
space out of the namespace directly
("--map=dev"). The overhead is 64-bytes per 4K (16GB per 1TB)
on x86.
Thanks
Zhijian
> + placed on regular memory (memmap_on_memory=0). This attribute
> + must be set before the device is handed over to the 'kmem'
