__rdtsc | Microsoft Learn
WEBAug 2, 2021 · Syntax. Return value. Requirements. Remarks. Show 2 more. Microsoft Specific. Generates the rdtsc instruction, which returns the processor time stamp. The processor time stamp records the number of clock cycles since the last reset.
Time Stamp Counter - Wikipedia
WEBTime Stamp Counter. The Time Stamp Counter ( TSC) is a 64-bit register present on all x86 processors since the Pentium. It counts the number of CPU cycles since its reset. The instruction RDTSC returns the TSC in EDX:EAX. In x86-64 mode, RDTSC also clears the upper 32 bits of RAX and RDX. Its opcode is 0F 31. [1]
RDTSC — Read Time-Stamp Counter - felixcloutier.com
WEBThe time stamp disable (TSD) flag in register CR4 restricts the use of the RDTSC instruction as follows. When the flag is clear, the RDTSC instruction can be executed at any privilege level; when the flag is set, the instruction can only be executed at privilege level 0. The time-stamp counter can also be read with the RDMSR instruction, when ...
How to count clock cycles with RDTSC in GCC x86?
WEBrdtsc counts reference cycles, not CPU core clock cycles. It counts at a fixed frequency regardless of turbo / power-saving, so if you want uops-per-clock analysis, use performance counters. rdtsc is exactly correlated with wall-clock time (except for system clock adjustments, so it's basically steady_clock ).
__rdtsc | Microsoft Learn
WEBJan 22, 2024 · この記事の内容. 構文. 戻り値. 要件. 解説. さらに 2 個を表示. Microsoft 固有の仕様. プロセッサのタイムスタンプを返す rdtsc 命令を生成します。. プロセッサのタイムスタンプには、前回のリセットからのクロックサイクル数が記録されます。.
WEBThe Intel time-stamp counter is a 64-bit MSR (model specific register) that is incremented every clock cycle. On reset, the time-stamp counter is set to zero. To access this counter, programmers can use the RDTSC (read time-stamp counter) instruction. This instruction loads the high-order 32 bits of the register into EDX, and the low-order 32 ...
X86-assembly/Instructions/rdtsc - aldeid
WEBNov 29, 2015 · The rdtsc (Read Time-Stamp Counter) instruction is used to determine how many CPU ticks took place since the processor was reset. Loads the current value of the processor's time-stamp counter into the EDX:EAX registers. It is commonly used as a timing defense (anti-debugging technique).
RDTSC | x86 Instruction Set Reference
WEBApr 18, 2019 · When the TSD flag is clear, the RDTSC instruction can be executed at any privilege level; when the flag is set, the instruction can only be executed at privilege level 0. (When in real-address mode, the RDTSC instruction is always enabled.) The time-stamp counter can also be read with the RDMSR instruction, when executing at privilege level 0.
The RDTSC Performance Timer written in C++
WEBJun 1, 2017 · The RDTSC is the IA-32/IA-64 (or x86/x64) instruction that loads the current value of the processors’ time stamp into EDX:EAX registers. RDTSC is short for “Read Time-Stamp Counter”. It returns the number of clock cycles since last reset. The modern complier Visual Studio has implemented the compiler intrinsic so you don’t have to ...
Why is RDTSC a virtualized instruction on modern processors?
WEBOct 12, 2011 · 8. Its common to use RDTSC to get fine-grained timing information, where the overhead of a virtualization trap would be quite significant. Most common use is to have two RDTSC instructions with a small amount of code between them, taking the difference of the times as the elapsed time (number of cycles) for the code sequence.
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