1 /* High precision, low overhead timing functions. x86 version. 2 Copyright (C) 2018-2022 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <https://www.gnu.org/licenses/>. */ 18 19 #ifndef _HP_TIMING_H 20 #define _HP_TIMING_H 1 21 22 #include <isa.h> 23 24 #if MINIMUM_ISA == 686 || MINIMUM_ISA == 8664 25 /* We indeed have inlined functions. */ 26 # define HP_TIMING_INLINE (1) 27 28 /* We use 64bit values for the times. */ 29 typedef unsigned long long int hp_timing_t; 30 31 /* That's quite simple. Use the `rdtsc' instruction. Note that the value 32 might not be 100% accurate since there might be some more instructions 33 running in this moment. This could be changed by using a barrier like 34 'cpuid' right before the `rdtsc' instruciton. But we are not interested 35 in accurate clock cycles here so we don't do this. 36 37 NB: Use __builtin_ia32_rdtsc directly since including <x86intrin.h> 38 makes building glibc very slow. */ 39 # ifdef USE_RDTSCP 40 /* RDTSCP waits until all previous instructions have executed and all 41 previous loads are globally visible before reading the counter. 42 RDTSC doesn't wait until all previous instructions have been executed 43 before reading the counter. */ 44 # define HP_TIMING_NOW(Var) \ 45 (__extension__ ({ \ 46 unsigned int __aux; \ 47 (Var) = __builtin_ia32_rdtscp (&__aux); \ 48 })) 49 # else 50 # define HP_TIMING_NOW(Var) ((Var) = __builtin_ia32_rdtsc ()) 51 # endif 52 53 # include <hp-timing-common.h> 54 #else 55 /* NB: Undefine _HP_TIMING_H so that <sysdeps/generic/hp-timing.h> will 56 be included. */ 57 # undef _HP_TIMING_H 58 # include <sysdeps/generic/hp-timing.h> 59 #endif 60 61 #endif /* hp-timing.h */ 62