Re: [PATCH 4/4] dax: "Hotplug" persistent memory for use like normal RAM

[Dave Hansen]

On 1/17/19 11:47 PM, Yanmin Zhang wrote:
> a chance for kernel to allocate PMEM as DMA buffer.
> Some super speed devices like 10Giga NIC, USB (SSIC connecting modem),
> might not work well if DMA buffer is in PMEM as it's slower than DRAM.
> 
> Should your patchset consider it?

No, I don't think so.

They can DMA to persistent memory whether this patch set exists or not.
 So, if the hardware falls over, that's a separate problem.

If an app wants memory that performs in a particular way, then I would
suggest those app find the NUMA nodes on the system that match their
needs with these patches:

> http://lkml.kernel.org/r/20190116175804.30196-1-keith.busch@xxxxxxxxx

and use the existing NUMA APIs to select that memory.