RFC: prepare for struct scatterlist entries without page backing

[Boaz Harrosh]

On 08/13/2015 05:40 PM, Christoph Hellwig wrote:
> On Wed, Aug 12, 2015 at 03:42:47PM +0300, Boaz Harrosh wrote:
>> The support I have suggested and submitted for zone-less sections.
>> (In my add_persistent_memory() patchset)
>>
>> Would work perfectly well and transparent for all such multimedia cases.
>> (All hacks removed). In fact I have loaded pmem (with-pages) on a VRAM
>> a few times and it is great easy fun. (I wanted to experiment with cached
>> memory over a pcie)
> 
> And everyone agree that it was both buggy and incomplete.
> 

What? No one ever said anything about bugs. Is the first ever I hear of it.
I was always in the notion that no one even tried it out.

I'm smoking these page-full nvidimms for more than a year. With RDMA to
pears and swap out to disks. So is not that bad I would say

> Dan has done a respin of the page backed nvdimm work with most of
> these comments addressed.
> 

I would love some comments. All I got so far is silence. (And I do not
like Dan's patches comments will come next week)

> I have to say I hate both pfn-based I/O [1] and page backed nvdimms with
> passion, so we're looking into the lesser evil with an open mind.
> 
> [1] not the SGL part posted here, which I think is quite sane.  The bio
>     side is much worse, though.
> 

What can I say. I like the page-backed nvdimms. And the long term for me
is 2M pages. I hope we can sit one day soon and you explain to me whats
evil about it. I would really really like to understand

Thanks though
Boaz