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c++ Programming Glossary: mfenceDifference between rdtscp, rdtsc : memory and cpuid / rdtsc? http://stackoverflow.com/questions/12631856/difference-between-rdtscp-rdtsc-memory-and-cpuid-rdtsc given e.g. rdtscp cpuid memory fence instructions mfence lfence ... etc. As an aside while using cpuid as a barrier before.. of the memory fence instructions. The Linux kernel uses mfence rdtsc on AMD platforms and lfence rdtsc on Intel. If you don't.. you don't want to bother with distinguishing between these mfence rdtsc works on both although it's slightly slower as mfence..
Does the semantics of `std::memory_order_acquire` requires processor instructions on x86/x86_64? http://stackoverflow.com/questions/18576986/does-the-semantics-of-stdmemory-order-acquire-requires-processor-instruction rsp eax 0x4613ec 0x005c mov eax 0x20 rsp 0x4613f0 0x0060 mfence 0x4613f3 0x0063 mov ebx 0x20 rsp Disassembler MSVS 2012 x86_64..
Why GCC does not use LOAD(without fence) and STORE+SFENCE for std::memory_order_seq_cst? http://stackoverflow.com/questions/19047327/why-gcc-does-not-use-loadwithout-fence-and-storesfence-for-stdmemory-order rsp eax 0x4613ec 0x005c mov eax 0x20 rsp 0x4613f0 0x0060 mfence As we know that MFENCE LFENCE SFENCE. Then this code we can.. cstring std atomic int a char b 64 void seq movl 0 a rip mfence int temp 0 a.store temp std memory_order_seq_cst void rel movl..
Can I force cache coherency on a multicore x86 CPU? http://stackoverflow.com/questions/558848/can-i-force-cache-coherency-on-a-multicore-x86-cpu to see if that is the case. If that is the case then an mfence instruction will force execution to pause until the value has.. the value has been written. Force example you can do an mfence before releasing a mutex to ensure another process doesn't begin.. of the processor cache hierarchy. This combined with an mfence should get the intended behavior. share improve this answer..
C++ Memory Barriers for Atomics http://stackoverflow.com/questions/8841738/c-memory-barriers-for-atomics memory barriers The windows MemoryBarrier The fence _mm_mfence The inline assembly asm volatile memory The intrinsic _ReadWriteBarrier.. improve this question Both MemoryBarrier MSVC and _mm_mfence supported by several compilers provide a hardware memory fence.. specific implementations for x86 x64 and IA64 where as _mm_mfence specifically uses the mfence SSE2 instruction so it's not always..
Does the semantics of `std::memory_order_acquire` requires processor instructions on x86/x86_64? http://stackoverflow.com/questions/18576986/does-the-semantics-of-stdmemory-order-acquire-requires-processor-instruction which requires LOCK XCHG or alternative MOV into memory MFENCE . Processor memory barriers instructions for x86 except CAS..
Why GCC does not use LOAD(without fence) and STORE+SFENCE for std::memory_order_seq_cst? http://stackoverflow.com/questions/19047327/why-gcc-does-not-use-loadwithout-fence-and-storesfence-for-stdmemory-order Consistency in x86 x86_64 LOAD without fence and STORE MFENCE LOAD without fence and LOCK XCHG MFENCE LOAD and STORE without.. fence and STORE MFENCE LOAD without fence and LOCK XCHG MFENCE LOAD and STORE without fence LOCK XADD 0 and STORE without fence.. memory Store Seq Cst LOCK XCHG alternative MOV into memory MFENCE Note there is an alternative mapping of C C 11 to x86 which..
Memory model ordering and visibility? http://stackoverflow.com/questions/7461484/memory-model-ordering-and-visibility immediate visibility to other threads and neither does an MFENCE instruction . The C 0x memory ordering constraints are just.. requires stronger ordering with either an MFENCE instruction or a LOCK prefixed instruction there is an implementation.. memory_order_seq_cst is not again requiring an MFENCE or LOCK ed instruction . An important effect of the ordering..
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