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mdbx: using atomic_yield() inside safe64_read() retry loop.

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Леонид Юрьев (Leonid Yuriev)
2025-09-09 22:26:08 +03:00
parent 4adba731f5
commit f2a5ca26a6
1 changed files with 32 additions and 30 deletions
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62
src/atomics-ops.h
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@@ -7,6 +7,33 @@
#ifndef __cplusplus
MDBX_MAYBE_UNUSED static __always_inline void atomic_yield(void) {
#if defined(_WIN32) || defined(_WIN64)
YieldProcessor();
#elif defined(__ia32__) || defined(__e2k__)
__builtin_ia32_pause();
#elif defined(__ia64__)
#if defined(__HP_cc__) || defined(__HP_aCC__)
_Asm_hint(_HINT_PAUSE);
#else
__asm__ __volatile__("hint @pause");
#endif
#elif defined(__aarch64__) || (defined(__ARM_ARCH) && __ARM_ARCH > 6) || defined(__ARM_ARCH_6K__)
#ifdef __CC_ARM
__yield();
#else
__asm__ __volatile__("yield");
#endif
#elif (defined(__mips64) || defined(__mips64__)) && defined(__mips_isa_rev) && __mips_isa_rev >= 2
__asm__ __volatile__("pause");
#elif defined(__mips) || defined(__mips__) || defined(__mips64) || defined(__mips64__) || defined(_M_MRX000) || \
defined(_MIPS_) || defined(__MWERKS__) || defined(__sgi)
__asm__ __volatile__(".word 0x00000140");
#else
osal_yield();
#endif
}
#ifdef MDBX_HAVE_C11ATOMICS
#define osal_memory_fence(order, write) atomic_thread_fence((write) ? mo_c11_store(order) : mo_c11_load(order))
#else /* MDBX_HAVE_C11ATOMICS */
@@ -144,38 +171,12 @@ MDBX_MAYBE_UNUSED static
if (likely(value == again))
return value;
value = again;
atomic_yield();
}
#endif /* !MDBX_64BIT_ATOMIC */
}
#endif /* atomic_load64 */
MDBX_MAYBE_UNUSED static __always_inline void atomic_yield(void) {
#if defined(_WIN32) || defined(_WIN64)
YieldProcessor();
#elif defined(__ia32__) || defined(__e2k__)
__builtin_ia32_pause();
#elif defined(__ia64__)
#if defined(__HP_cc__) || defined(__HP_aCC__)
_Asm_hint(_HINT_PAUSE);
#else
__asm__ __volatile__("hint @pause");
#endif
#elif defined(__aarch64__) || (defined(__ARM_ARCH) && __ARM_ARCH > 6) || defined(__ARM_ARCH_6K__)
#ifdef __CC_ARM
__yield();
#else
__asm__ __volatile__("yield");
#endif
#elif (defined(__mips64) || defined(__mips64__)) && defined(__mips_isa_rev) && __mips_isa_rev >= 2
__asm__ __volatile__("pause");
#elif defined(__mips) || defined(__mips__) || defined(__mips64) || defined(__mips64__) || defined(_M_MRX000) || \
defined(_MIPS_) || defined(__MWERKS__) || defined(__sgi)
__asm__ __volatile__(".word 0x00000140");
#else
osal_yield();
#endif
}
#if MDBX_64BIT_CAS
MDBX_MAYBE_UNUSED static __always_inline bool atomic_cas64(mdbx_atomic_uint64_t *p, uint64_t c, uint64_t v) {
#ifdef MDBX_HAVE_C11ATOMICS
@@ -312,10 +313,11 @@ MDBX_MAYBE_UNUSED static __always_inline void safe64_write(mdbx_atomic_uint64_t
MDBX_MAYBE_UNUSED static __always_inline uint64_t safe64_read(const mdbx_atomic_uint64_t *p) {
jitter4testing(true);
uint64_t v;
do
uint64_t v = atomic_load64(p, mo_AcquireRelease);
while (!MDBX_64BIT_ATOMIC && unlikely(v != p->weak)) {
atomic_yield();
v = atomic_load64(p, mo_AcquireRelease);
while (!MDBX_64BIT_ATOMIC && unlikely(v != p->weak));
}
return v;
}