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Use an isb as a pause instruction on arm64 platforms. #441

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Use an isb as a pause instruction on arm64 platforms. #441

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6 changes: 5 additions & 1 deletion src/fastlock.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -379,7 +379,11 @@ extern "C" void fastlock_lock(struct fastlock *lock, spin_worker worker)
#if defined(__i386__) || defined(__amd64__)
__asm__ __volatile__ ("pause");
#elif defined(__aarch64__)
__asm__ __volatile__ ("yield");
/* Use an isb here as we've found it's much closer in duration to
* the x86 pause instruction vs. yield which is a nop and thus the
* loop count is lower and the interconnect gets a lot more traffic
* from loading the ticket above. */
__asm__ __volatile__ ("isb");
#endif

if ((++cloops % loopLimit) == 0)
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