x86-64

In the following pseudo-code: if (rdtscp supported by hardware) { Invoke "rdtscp" instruction } else { Invoke "rdtsc" instruction } Let's say the CPU does not support the rdtscp instruction and so we fallback to the else statement. If CPU mispredicts the branch, is it possible for the instruction pipeline to try to execute rdtscp and throw an Illgal Instruction error? It is explicitly documented for the #UD trap (Invalid Opcode Execution) in the Intel Processor Manuals, Volume 3A, chapter 6.15: In Intel 64 and IA-32 processors that implement out-of-order execution microarchitectures, this

进官网根据不同的操作系统，下载适合自己的编译环境（在百度里直接输入Python） 选择安装包（我选择的是3.8.0版本） python官方下载目录中有好多种安装方式，一般情况选择Windows x86-64 executable installer Download Windows x86 web-based installer–基于网络安装 Download Windows x86 executable installer–安装文件 Download Windows x86 embeddable zip file–压缩包 Download Windows x86-64 web-based installer–64位基于网络安装 Download Windows x86-64 executable installer–64位安装文件 Download Windows x86-64 embeddable zip file–64位压缩包 安装过程： 为了不去设置环境变量，我选择Customize installation安装，并且勾选Add Python 3.8 to PATH。 选择安装路径，我安装到D:\Program Files\Python3下面。 安装完成： 测试是否安装成功（输入“Python”，如果提示相应的版本号和一些指令，说明你的Python就已经安装好了

unsigned int lo = 0; unsigned int hi = 0; __asm__ __volatile__ ( "mfence;rdtsc" : "=a"(lo), "=d"(hi) : : "memory" ); mfence in the above code, is it necessary? Based on my test, cpu reorder is not found. The fragment of test code is included below. inline uint64_t clock_cycles() { unsigned int lo = 0; unsigned int hi = 0; __asm__ __volatile__ ( "rdtsc" : "=a"(lo), "=d"(hi) ); return ((uint64_t)hi << 32) | lo; } unsigned t1 = clock_cycles(); unsigned t2 = clock_cycles(); assert(t2 > t1); What you need to perform a sensible measurement with rdtsc is a serializing instruction. As it is well known

Background : I'm trying to implement a system like that described in this previous answer . In short, I have an application that links against a shared library (on Linux at present). I would like that shared library to switch between multiple implementations at runtime (for instance, based on whether the host CPU supports a certain instruction set). In its simplest case, I have three distinct shared library files: libtest.so : This is the "vanilla" version of the library that will be used as a fallback case. libtest_variant.so : This is the "optimized" variant of the library that I would like

I've read that RDTSC can gives false readings and should not be relied upon. Is this true and if so what can be done about it? Very old CPU's have a RDTSC that is accurate. The problem However newer CPU's have a problem. Engineers decided that RDTSC would be great for telling time. However if a CPU throttles the frequency RDTSC is useless for telling time. The aforementioned braindead engineers then decided to 'fix' this problem by having the TSC always run at the same frequency, even if the CPU slows down. This has the 'advantage' that TSC can be used for telling elapsed (wall clock) time.

I am trying to create an x86_64 assembly program that displays "SIGTERM received" whenever the SIGTERM signal is sent. My application is using Linux syscalls directly: %define sys_write 0x01 %define sys_rt_sigaction 0x0d %define sys_pause 0x22 %define sys_exit 0x3c %define SIGTERM 0x0f %define STDOUT 0x01 ; Definition of sigaction struct for sys_rt_sigaction struc sigaction .sa_handler resq 1 .sa_flags resq 1 .sa_restorer resq 1 .sa_mask resq 1 endstruc section .data ; Message shown when a syscall fails error_msg db 'syscall error', 0x0a error_msg_len equ $ - error_msg ; Message shown when