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Added initial code base.
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‎Makefile

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#
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# libbenchtsc is a simple benchmarking library that uses the rdtsc
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# x86 instruction.
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# Copyright (c) 2014, Simon Gerber <[email protected]>
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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#
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CFLAGS=-Wall -O2 -std=gnu11
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PREFIX=/home/gerbesim/.local
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VERSION=1
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MINOR=0
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LIBFNAME=libbenchtsc.so.$(VERSION).$(MINOR)
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LIBSONAME=libbenchtsc.so.$(VERSION)
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$(LIBFNAME): bench_rdtsc.o
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gcc $(CFLAGS) -shared -Wl,-soname,$(LIBSONAME) -o $(LIBFNAME) bench_rdtsc.o -lm
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bench_rdtsc.o: bench_rdtsc.c
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gcc $(CFLAGS) -fpic -fPIC -c bench_rdtsc.c
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install: $(LIBFNAME) bench_rdtsc.h
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install -m 644 -C $(LIBFNAME) -D $(PREFIX)/lib/$(LIBFNAME)
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ldconfig -l $(PREFIX)/lib/$(LIBFNAME)
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mkdir -p $(PREFIX)/include
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install -m 644 -C bench_rdtsc.h $(PREFIX)/include
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‎bench_rdtsc.c

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/*
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* libbenchtsc is a simple benchmarking library that uses the rdtsc
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* x86 instruction.
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* Copyright (c) 2014, Simon Gerber <[email protected]>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "bench_rdtsc.h"
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#include <time.h>
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double ticks_per_nano = 0.0;
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bool rdtscp_flag = false;
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const int NANO_SECONDS_IN_SEC = 1000000000;
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/* returns a static buffer of struct timespec with the time difference of ts1 and ts2
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ts1 is assumed to be greater than ts2 */
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static struct timespec *TimeSpecDiff(struct timespec *ts1, struct timespec *ts2)
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{
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static struct timespec ts;
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ts.tv_sec = ts1->tv_sec - ts2->tv_sec;
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ts.tv_nsec = ts1->tv_nsec - ts2->tv_nsec;
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if (ts.tv_nsec < 0) {
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ts.tv_sec--;
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ts.tv_nsec += NANO_SECONDS_IN_SEC;
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}
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return &ts;
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}
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static void calibrate_ticks(void)
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{
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struct timespec begints, endts;
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uint64_t begin = 0, end = 0;
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clock_gettime(CLOCK_MONOTONIC, &begints);
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begin = bench_tsc();
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uint64_t i;
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for (i = 0; i < 1000000; i++); /* must be CPU intensive */
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end = bench_tsc();
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clock_gettime(CLOCK_MONOTONIC, &endts);
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struct timespec *tmpts = TimeSpecDiff(&endts, &begints);
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uint64_t nsecElapsed = tmpts->tv_sec * 1000000000LL + tmpts->tv_nsec;
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ticks_per_nano = (double)(end - begin)/(double)nsecElapsed;
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}
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void bench_init(void)
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{
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uint32_t eax, ebx, ecx, edx;
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// Check for rdtscp instruction
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cpuid(0x80000001, &eax, &ebx, &ecx, &edx);
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if ((edx >> 27) & 1) {
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rdtscp_flag = true;
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} else {
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rdtscp_flag = false;
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}
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calibrate_ticks();
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}
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struct bench_calc_st {
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double *series;
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int runs;
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double avg;
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double sdev;
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};
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static void calculate_(double *measurements, int runs, struct bench_calc_st *st)
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{
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double mean = 0.0, M2 = 0.0;
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for (int i = 0; i < runs; i++) {
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double delta = measurements[i] - mean;
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mean = mean + delta / (i+1);
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M2 = M2 + delta*(measurements[i]-mean);
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}
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st->series = measurements;
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st->runs = runs;
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st->avg = mean;
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st->sdev = sqrt(M2/(runs-1));
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}
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double bench_avg(double *measurements, int runs, struct bench_calc_st *st)
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{
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struct bench_calc_st tmp = { 0 };
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if (!st) {
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st = &tmp;
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}
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if (st->series != measurements || st->runs != runs) {
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calculate_(measurements, runs, st);
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}
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return st->avg;
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}
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double bench_sdev(double *measurements, int runs, struct bench_calc_st *st)
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{
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struct bench_calc_st tmp = { 0 };
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if (!st) {
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st = &tmp;
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}
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if (st->series != measurements || st->runs != runs) {
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calculate_(measurements, runs, st);
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}
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return st->sdev;
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}
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size_t bench_calc_st_sz(void)
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{
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return sizeof(struct bench_calc_st);
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}

‎bench_rdtsc.h

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/*
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* libbenchtsc is a simple benchmarking library that uses the rdtsc
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* x86 instruction.
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* Copyright (c) 2014, Simon Gerber <[email protected]>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef BENCH_RDTSC_H
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#define BENCH_RDTSC_H
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#include <math.h>
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#include <stdbool.h>
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#include <inttypes.h>
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#include <stdlib.h>
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extern bool rdtscp_flag;
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extern double ticks_per_nano;
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static inline uint64_t rdtscp(void)
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{
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uint32_t eax, edx;
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__asm volatile ("rdtscp" : "=a" (eax), "=d" (edx) :: "ecx");
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return ((uint64_t)edx << 32) | eax;
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}
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static inline uint64_t rdtsc(void)
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{
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uint32_t eax, edx;
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__asm volatile ("rdtsc" : "=a" (eax), "=d" (edx));
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return ((uint64_t)edx << 32) | eax;
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}
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static inline uint64_t bench_tsc()
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{
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if (rdtscp_flag) {
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return rdtscp();
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} else {
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return rdtsc();
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}
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}
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static inline void cpuid(uint32_t function, uint32_t *eax, uint32_t *ebx,
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uint32_t *ecx, uint32_t *edx)
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{
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// make it possible to omit certain return registers
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uint32_t a, b, c, d;
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if (eax == NULL) {
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eax = &a;
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}
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if (ebx == NULL) {
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ebx = &b;
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}
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if (ecx == NULL) {
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ecx = &c;
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}
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if (edx == NULL) {
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edx = &d;
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}
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__asm volatile("cpuid"
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: "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
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: "a" (function)
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);
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}
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static inline double bench_tsc_to_ms(uint64_t tsc)
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{
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return tsc / (ticks_per_nano * 1e6);
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}
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void bench_init(void);
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struct bench_calc_st;
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double bench_avg(double *measurements, int runs, struct bench_calc_st *st);
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double bench_sdev(double *measurements, int runs, struct bench_calc_st *st);
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size_t bench_calc_st_sz(void);
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#endif // BENCH_RDTSC_H

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