4 ms·
Very interesting. I've seen a similar idea proposed to enable shared-memory based RPC, instead of communicating over a socket both processes agree to "trade" a
by traverseda 7y ago
Very interesting. I've seen a similar idea proposed to enable shared-memory based RPC, instead of communicating over a socket both processes agree to "trade" a chunk of memory back and forth, using it as a buffer for RPC messages.
- dragontamer 7y agoIts becoming clear that DDR4 RAM is "just another I/O system". RAM has always forced CPUs to stall: refresh events are the most common (RAM is refreshing the voltage on all memory: it takes a long time and the CPU may have to wait in rare cases). But modern multicore CPUs have to have this coherency fabric to ensure that the different cores see memory in the correct order. It doesn't really matter if the CPU is stalling because of a memory refresh, or a CPU-exclusive hold on some RAM... or even I/O pretending to be a CPU-core holding some RAM. The CPU's method of attack remains the same. ------- This is most clear with Intel's Optane DIMMs, persistent storage that operates over the DDR4 protocol, pretending to be RAM. Slower than true DDR4 yes, but fast enough that it wanted to move off of PCIe and pretend to be DDR4 RAM. I expect more and more I/O to be "pretending to be RAM" in some effect, either through a coherency fabric or maybe even just copying the DDR4 protocol (like Optane).