Directly mapped persistent storage ...
... + Spectre + Meltdown (or their latest equivalents). What could possibly go wrong?
Semiconductor analyst David Kanter has identified six areas of ignorance about Intel's Optane DIMMs where clarity will dictate whether they become popular or not. Optane is a brand name for Intel's 3D XPoint memory, the storage technology that can be found in its P4800X series SSDs. The name has been slapped on Intel's …
persistant ram is going to need a whole new programming model to be used effectively I feel.
storage is ram, and ram is storage. do a reboot/power off-on and just wait for the CPU to come back on line and carry on as you were. your machine is effectively going to be "on" from the first OS install to the final switch off. apps get loaded into memory and stay there. 512gig on a dimm? no paging? no "disk"?yes please!
BSODs gonna be a pain though.
We could have a little hole on the side of the device to poke a small pen into. Naturally, the first product will be from Apple who will claim to have invented the idea.
But you won't be able to just use any pen, it will have to be an Apple iPen with security keys, costing £000s. There also won't be a hole, the iPen will operate wirelessly, and not work with anything but Apple products.
Yes, the industry is aware of some of the outstanding problems. From a security perspective, JEDEC are working on a spec for self encrypting NVDIMMs. We'll have a solution shortly.
There is a huge amount of other information at https://www.snia.org/forums/sssi/nvmp (Non Volatile Memory (NVM) Programming Technical Work Group) that does technical work, and https://www.snia.org/forums/sssi/NVDIMM (Persistent Memory and NVDIMM Special Interest Group) that has a large selection of educational material on this subject. There is a regular conference on Persistent Memory run every year; more information, including all the presentations inclduing the last 2018 confernece are here https://www.snia.org/pm-summit
(Alex, Co-chair, SNIA Solid State Storage Initiative)
On my AMD Bulldozer era system using DDR3, DRAM speed is very sensitive to the number of loads on the memory bus. By limiting memory to only 2 of the 4 available slots, my system can maintain 1600 MHz speed. If I occupy all 4 slots with the exact same memory, speed drops to 1066 MHz on all slots.
I'm assuming the constraints with loads still holds true with NVDIMMs? I did a quick search on the topic, and couldn't find any information. Seems to lessen the appeal if adding NVDIMMs slows down the entire memory bus.
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