How to count clock cycles with RDTSC in GCC x86?
WEBHow to get the CPU cycle count in x86_64 from C++? (5 answers) Closed 5 years ago. With Visual Studio I can read the clock cycle count from the processor as shown below. How do I do the same thing with GCC? #ifdef _MSC_VER // Compiler: Microsoft Visual Studio. #ifdef _M_IX86 // Processor: x86.
Time Stamp Counter - Wikipedia
WEBThe 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 | Microsoft Learn
WEBRequirements. 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. Syntax. Copy. unsigned __int64 __rdtsc(); Return value. A 64-bit unsigned integer representing a tick count. Requirements. Expand table.
RDTSC — Read Time-Stamp Counter - felixcloutier.com
WEBRDTSC — Read Time-Stamp Counter. Instruction Operand Encoding ¶. Description ¶. Reads the current value of the processor’s time-stamp counter (a 64-bit MSR) into the EDX:EAX registers. The EDX register is loaded with the high-order 32 bits of the MSR and the EAX register is loaded with the low-order 32 bits.
WEBProgrammers are often puzzled by the erratic performance numbers they see when using the RDTSC (read-time stamp counter) instruction to monitor performance. This erratic behavior is not an instruction flaw; the RDTSC instruction will always give back a …
Difference between rdtscp, rdtsc : memory and cpuid / rdtsc?
WEBSep 28, 2012 · 1: rdtscp is a serializing call. It prevents reordering around the call to rdtscp. __asm__ __volatile__("rdtscp; " // serializing read of tsc. "shl $32,%%rdx; " // shift higher 32 bits stored in rdx up. "or %%rdx,%%rax" // and or onto rax. : …
Why is RDTSC a virtualized instruction on modern processors?
WEBOct 12, 2011 · Why is RDTSC a virtualized instruction on modern processors? Asked 12 years, 7 months ago. Modified 12 years, 7 months ago. Viewed 6k times. 6. I am studying RDTSC and learning about how it is virtualized for the purposes of virtual machines like VirtualBox and VMWare. Why did Intel/AMD go to all the trouble of virtualizing this …
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). Opcode. 0F 31. Flags affected. None. Example.
Performance measurements with RDTSC - strchr.com
WEBThe RDTSC instruction returns a 64-bit time stamp counter (TSC), which is increased on every clock cycle. It's the most precise counter available on x86 architecture. MSVC++ 2005 compiler supports a handy __rdtsc intrinsic that returns the result in 64-bit variable.
__rdtscp | Microsoft Learn
WEBAug 2, 2021 · Remarks. Show 2 more. Microsoft Specific. Generates the rdtscp instruction, writes TSC_AUX[31:0] to memory, and returns the 64-bit Time Stamp Counter (TSC) result. Syntax. Copy. unsigned __int64 __rdtscp( unsigned int * AUX. ); Parameters. AUX.
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