Accessing raw CPUID information is actually very easy, here is a C++ class for that which works in Windows, Linux and OSX: #ifndef CPUID_H #define CPUID_H #ifdef _WIN32 #include <limits.h> #include <intrin.h> typedef unsigned __int32 uint32_t; #else #include <stdint.h> #endif class CPUID { uint32_t regs[4]; public: explicit CPUID(unsigned i) { #ifdef _WIN32 __cpuid((int *)regs, (int)i); … 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
Potentially depends on the CPU. However, all modern CPUs (x86, ARM) use a “barrel shifter” — a hardware module specifically designed to perform arbitrary shifts in constant time. So the bottom line is… no. No difference.
What led me here is checking for a 32 vs 64 bit OS. the highest rated answer is looking at the setting for the Current process. After not finding an answer I found the following setting. Hope this works for you. bool is64 = System.Environment.Is64BitOperatingSystem
System.Environment.ProcessorCount returns the number of logical processors http://msdn.microsoft.com/en-us/library/system.environment.processorcount.aspx For physical processor count you’d probably need to use WMI – the following metadata is supported in XP/Win2k3 upwards (Functionality enabled in SP’s prior to Vista/Win2k8). Win32_ComputerSystem.NumberOfProcessors returns physical count Win32_ComputerSystem.NumberOfLogicalProcessors returns logical (duh!) Be cautious that HyperThreaded CPUs appear identical to multicore’d CPU’s yet the performance … Read more
I’ll expand on my comments here. This is too big and in-depth for me to fit in the comments. What you’re trying to do is very difficult – to the point of being impractical for the following reasons: There’s no portable way to get the processor frequency. rdtsc does NOT always give the correct frequency … Read more
#include <unistd.h> long number_of_processors = sysconf(_SC_NPROCESSORS_ONLN);
According the htop source code, my assumptions looks like they are valid: (see static inline double LinuxProcessList_scanCPUTime(LinuxProcessList* this) function at LinuxProcessList.c) // Guest time is already accounted in usertime usertime = usertime – guest; # As you see here, it subtracts guest from user time nicetime = nicetime – guestnice; # and guest_nice from nice … Read more
A core is usually the basic computation unit of the CPU – it can run a single program context (or multiple ones if it supports hardware threads such as hyperthreading on Intel CPUs), maintaining the correct program state, registers, and correct execution order, and performing the operations through ALUs. For optimization purposes, a core can … Read more
I use stress for this kind of thing, you can tell it how many cores to max out.. it allows for stressing memory and disk as well. Example to stress 2 cores for 60 seconds stress –cpu 2 –timeout 60