One of the drawbacks of a Raspberry Pi is its lack of an on-board clock. After a reboot, its clock is set to midnight, New Year’s Day, 1970 UTC, the beginning of the Unix epoch, and then the kernel boots. However, it is possible to get the current time early in the boot process, with one condition: an NFS root filesystem.
I know it’s been, oh, over a year since my last post. It’s been kind of like the Olympic gold medalist’s let-down: what do I do now? I’ve done a lot of tinkering, and “what happens if I do this?” kind of stuff, but nothing really big.
But this afternoon, I read about Intel’s new 14-nanometer process for making a CPU, giving 52-nm interconnects. Now, given that the covalent diameter of silicon is 222 picometers, a 52-nm interconnect would be:
52000 / 222 = 234 silicon atoms wide.
The mind boggles.
The ARM VFP co-processor is most commonly used for individual floating-point computations, in the so-called “scalar mode.” In Flynn’s taxonomy, this is known as SISD, or “single instruction, single destination.” This design philosophy is the basic form for most low-level assembly most high-level compilers. In cases where different data sources are treated differently, for whatever reason, SISD is the norm.
However, when a block of identical operations are carried out on a sequence of data points, then it is possible to fetch several of the source data, and perform the operations on them all at once. This may be something as simple as adding the values of two arrays and storing the results into a third array, which may be part of a sophisticated analysis on a digital image. A close examination of the processing can show where Single Instruction, Multiple Destination (SIMD) design can boost a program’s performance.