There’s a great article on Wikipedia about the differences and benefits of 64bit Intel/AMD cpus over their 32 bit versions. It should have all the information you need. Some on the key differences are: 16 general purpose registers instead of 8 Additional SSE registers A no execute (NX) bit to prevent buffer overrun attacks
AMD processor in the early-gigahertz era had a 40 cycle penalty every time you called a function Huh.. so large.. There is an “Indirect branch prediction” method, which helps to predict virtual function jump, IF there was the same indirect jump some time ago. There is still a penalty for first and mispredicted virt. function … Read more
That depends entirely on the ISA you’re compiling for, and the quality of your compiler’s optimizer. Don’t optimize prematurely: profile first to find your bottlenecks. That said, in x86, you’ll find that both are equally fast in most cases. In both cases, you’ll have a comparison (cmp) and a conditional jump (jCC) instructions. However, for … Read more
You can also use System.Diagnostics.Process.TotalProcessorTime and System.Diagnostics.ProcessThread.TotalProcessorTime properties to calculate your processor usage as this article describes.
Register banking refers to providing multiple copies of a register at the same address. Taken from section 1.4.6 of the arm docs The term is referring to a solution for the problem that not all registers can be seen at once. There is a different register bank for each processor mode. The banked registers give … Read more
Both CPUs & GPUs provide SIMD with the most standard conceptual unit being 16 bytes/128 bits; for example a Vector of 4 floats (x,y,z,w). Simplifying: CPUs then parallelize more through pipelining future instructions so they proceed faster through a program. Then next step is multiple cores which run independent programs. GPUs on the other hand … Read more
In older architectures, peripherals were accessed via a separate mechanism to memory access with special I/O instructions. On x86, there were (and still are!) “in” and “out” instructions for transferring bytes between the CPU and a peripheral. Peripherals were given addresses, for example 0x80 for the keyboard. Simplifying a lot, doing “in 0x80” would read … Read more
I don’t believe there’s anything within .NET to allow copying a section of a file without buffering it in memory. However, it strikes me that this is inefficient anyway, as it needs to open the input file and seek many times. If you’re just splitting up the file, why not open the input file once, … Read more
Some instruction sets are limited to one bit shift per instruction. And some instruction sets allow you to specify any number of bits to shift in one instruction, which usually takes one clock cycle on modern processors (modern being an intentionally vague word). See dan04’s answer about a barrel shifter, a circuit that shifts more … Read more
The closest answer I found so far is this one: For a single-threaded program, a cpu usage of 0.1 means that if you could freeze the machine at a random moment in time, and look at what each core is doing, there is a 1 in 10 chance that your single thread is running at … Read more