malloclab start

malloclab/clock.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#ifdef _WIN32
+#include <windows.h>
+#include <intrin.h>
+#else
+#include <unistd.h>
+#endif
+#include "clock.h"
+
+void start_counter(void);
+double get_counter(void);
+
+/*
+ * Routines for using the cycle counter
+ */
+
+ /* $begin x86cyclecounter */
+ /* Initialize the cycle counter */
+static unsigned cyc_hi = 0;
+static unsigned cyc_lo = 0;
+
+
+/* Set *hi and *lo to the high and low order bits  of the cycle counter.
+   Implementation requires assembly code to use the rdtsc instruction. */
+void access_counter(unsigned* hi, unsigned* lo)
+{
+#ifdef _WIN32
+	long long counter;
+	counter = __rdtsc();
+	(*hi) = (unsigned int)(counter >> 32);
+	(*lo) = (unsigned int)counter;
+#else
+	asm("rdtsc; movl %%edx,%0; movl %%eax,%1"   /* Read cycle counter */
+		: "=r" (*hi), "=r" (*lo)                /* and move results to */
+		: /* No input */                        /* the two outputs */
+		: "%edx", "%eax");
+#endif
+}
+
+/* Record the current value of the cycle counter. */
+void start_counter(void)
+{
+	access_counter(&cyc_hi, &cyc_lo);
+}
+
+/* Return the number of cycles since the last call to start_counter. */
+double get_counter(void)
+{
+	unsigned ncyc_hi, ncyc_lo;
+	unsigned hi, lo, borrow;
+	double result;
+
+	/* Get cycle counter */
+	access_counter(&ncyc_hi, &ncyc_lo);
+
+	/* Do double precision subtraction */
+	lo = ncyc_lo - cyc_lo;
+	borrow = lo > ncyc_lo;
+	hi = ncyc_hi - cyc_hi - borrow;
+	result = (double)hi * (1 << 30) * 4 + lo;
+	if (result < 0) {
+		printf("[%s]错误！counter返回了负值：%.0f\n", __func__, result);
+	}
+	return result;
+}
+
+void make_CPU_busy(void)
+{
+	volatile double old_tick, new_tick;
+	start_counter();
+	old_tick = get_counter();
+	new_tick = get_counter();
+	while (new_tick - old_tick < 1000000000)
+		new_tick = get_counter();
+}
+
+/* $begin mhz */
+/* Estimate the clock rate by measuring the cycles that elapse */
+/* while sleeping for sleeptime seconds */
+double mhz_full(int verbose, int sleeptime)
+{
+	double rate;
+
+	if (verbose)
+		printf("[%s]准备开始测量处理器性能，睡眠时间=%d秒\n", __func__, sleeptime);
+	start_counter();
+#ifdef _WIN32
+	Sleep(sleeptime * 1000);
+#else
+	sleep(sleeptime);
+#endif
+	rate = get_counter() / (1e6 * sleeptime);
+	if (verbose)
+		printf("[%s]处理器主频 ~= %.1f MHz\n", __func__, rate);
+	return rate;
+}
+/* $end mhz */
+
+/* Version using a default sleeptime */
+double mhz(int verbose)
+{
+	return mhz_full(verbose, 2);
+}
+
+