1. PMM working group

2. System Issues giant address space effects Kernel ABI Page migration
Can you boot with large pages?
Cache based on physical addresses, not user-controllable—only kernel
Degradation over time due to page fragmentation and collisions
Add scrambler to reduce collisions
VMM subsystem has linear algorithms that don’t scale to this address space
Large pages: algorithms behave differently
Cache line sizes change radically—generally, should assume cache line size is variable

3. System Issues, cont’d
Persistent memory as quasi-disk requires serialization, not just raw pointers
System-level support for persistent memory as opposed to fast disk?
What new tricks does mmap need?
Does disk go away on these systems?
Kernel tricks for I/O enabled by persistent memory?
Calloc()ing ½ TB: not the best idea without clever implementation behind it (lazy clear)
Network operations (RDMA etc)—when is it safe to report data was written?
Core/crash dumps at N TB: how do we support this?

4. Application level issues/questions
What do users need from tools to decide:
Will Optane help?
Which mode is best suited?
How do we optimize access patterns?
Can’t use serial tools within/alongside our apps
E.g. gzip has to be parallel when unzipping giant datasets
All utilities operating on large datasets or binaries need to be parallelized
Working set size has exploded: what are the implications for tools?
Sampling-based approaches may become mandatory
Implications for job transition times and use in general-purpose clusters?
Sharing persistent memory?
Long run times, long eviction times?
To what extent is pipelining possible?
Known ratios of RAM/core will change radically: what effects on application design?

5. Power behavior of Optane
What do we already know?
Cost vs. DRAM, SSD, HDD
Static vs. dynamic costs
What support is present for measurement?
What support is needed but not yet present?