11
© The Author(s) 2020
S. Scargall, Programming Persistent Memory, https://doi.org/10.1007/978-1-4842-4932-1_2
CHAPTER 2
Persistent Memory
Architecture
This chapter provides an overview of the persistent memory architecture while focusing
on the hardware to emphasize requirements and decisions that developers need to know.
Applications that are designed to recognize the presence of persistent memory in
a system can run much faster than using other storage devices because data does not
have to transfer back and forth between the CPU and slower storage devices. Because
applications that only use persistent memory may be slower than dynamic randomaccess memory (DRAM), they should decide what data resides in DRAM, persistent
memory, and storage.
The capacity of persistent memory is expected to be many times larger than DRAM;
thus, the volume of data that applications can potentially store and process in place is
also much larger. This significantly reduces the number of disk I/Os, which improves
performance and reduces wear on the storage media.
On systems without persistent memory, large datasets that cannot fit into DRAM
must be processed in segments or streamed. This introduces processing delays as the
application stalls waiting for data to be paged from disk or streamed from the network.
If the working dataset size fits within the capacity of persistent memory and DRAM,
applications can perform in-memory processing without needing to checkpoint or page
data to or from storage. This significantly improves performance.