Re: [PATCH] eal: add request to map reserved physical memory

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 28-Mar-18 5:51 AM, Ajit Khaparde wrote:
> From: Srinath Mannam <srinath.mannam@broadcom.com>
> 
> Reserved physical memory is requested from kernel
> and it will be mapped to user space.
> This memory will be mapped to IOVA using VFIO.
> And this memory will be provided to SPDK to allocate
> NVMe CQs.
> 
> Signed-off-by: Srinath Mannam <srinath.mannam@broadcom.com>
> Signed-off-by: Scott Branden <scott.branden@broadcom.com>
> Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
> ---

Hi Srinath,

I've seen this kind of approach implemented before to add additional 
memory types to DPDK (redefining "unused" socket id's to mean something 
else), and i don't like it.

What would be better is to design a new API to support different memory 
types. Some groundwork for this was already laid for this release 
(switching to memseg lists), but more changes will be needed down the 
line. My ideal approach would be to have pluggable memory allocators. 
I've outlined some of my thoughts on this before [1], you're welcome to 
join/continue that discussion, and make sure whatever comes out of it is 
going to be useful for all of us :) I was planning to (attempt to) 
restart that discussion, and this seems like as good an opportunity to 
do that as any other.

Now that the memory hotplug stuff is merged, i'll hopefully get more 
time prototyping.

So, as it is, it's a NACK from me, but let's work together on something 
better :)

[1] http://dpdk.org/ml/archives/dev/2018-February/090937.html

-- 
Thanks,
Anatoly