Index: runtime/src/kmp.h =================================================================== --- runtime/src/kmp.h +++ runtime/src/kmp.h @@ -1040,7 +1040,11 @@ #if KMP_ARCH_X86 extern void __kmp_x86_pause(void); #elif KMP_MIC -static void __kmp_x86_pause(void) { _mm_delay_32(100); } +// Performance testing on KNC (C0QS-7120 P/A/X/D, 61-core, 16 GB Memory) showed +// regression after removal of extra PAUSE from KMP_YIELD_SPIN(). Changing +// the delay from 100 to 300 showed even better performance than double PAUSE +// on Spec OMP2001 and LCPC tasking tests, no regressions on EPCC. +static void __kmp_x86_pause(void) { _mm_delay_32(300); } #else static void __kmp_x86_pause(void) { _mm_pause(); } #endif @@ -1076,7 +1080,7 @@ KMP_CPU_PAUSE(); \ (count) -= 2; \ if (!(count)) { \ - KMP_YIELD(cond); \ + __kmp_yield(cond); \ (count) = __kmp_yield_next; \ } \ } @@ -1085,7 +1089,7 @@ KMP_CPU_PAUSE(); \ (count) -= 2; \ if (!(count)) { \ - KMP_YIELD(1); \ + __kmp_yield(1); \ (count) = __kmp_yield_next; \ } \ } Index: runtime/src/kmp_wait_release.h =================================================================== --- runtime/src/kmp_wait_release.h +++ runtime/src/kmp_wait_release.h @@ -47,7 +47,7 @@ */ template class kmp_flag { volatile P - *loc; /**< Pointer to the flag storage that is modified by another thread + *loc; /**< Pointer to the flag storage that is modified by another thread */ flag_type t; /**< "Type" of the flag in loc */ public: @@ -225,11 +225,14 @@ // If we are oversubscribed, or have waited a bit (and // KMP_LIBRARY=throughput), then yield - KMP_YIELD(oversubscribed); // TODO: Should it be number of cores instead of thread contexts? Like: // KMP_YIELD(TCR_4(__kmp_nth) > __kmp_ncores); // Need performance improvement data to make the change... - KMP_YIELD_SPIN(spins); + if (oversubscribed) { + KMP_YIELD(1); + } else { + KMP_YIELD_SPIN(spins); + } // Check if this thread was transferred from a team // to the thread pool (or vice-versa) while spinning. in_pool = !!TCR_4(this_thr->th.th_in_pool);