2 * Copyright (c) 1996 Bruce D. Evans.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
32 #include <sys/param.h>
33 #include <sys/systm.h>
36 #include <sys/eventhandler.h>
38 #include <sys/kernel.h>
40 #include <sys/sysctl.h>
42 #include <machine/clock.h>
43 #include <machine/timerreg.h>
45 #define CPUTIME_CLOCK_UNINITIALIZED 0
46 #define CPUTIME_CLOCK_I8254 1
47 #define CPUTIME_CLOCK_TSC 2
48 #define CPUTIME_CLOCK_I8254_SHIFT 7
50 int cputime_bias = 1; /* initialize for locality of reference */
52 static int cputime_clock = CPUTIME_CLOCK_UNINITIALIZED;
53 static int cputime_prof_active;
64 .type __mcount,@function \n\
67 # Check that we are profiling. Do it early for speed. \n\
69 cmpl $GMON_PROF_OFF,_gmonparam+GM_STATE \n\
72 # __mcount is the same as [.]mcount except the caller \n\
73 # hasn't changed the stack except to call here, so the \n\
74 # caller's raddr is above our raddr. \n\
83 movq 7*8+8(%rsp),%rdi \n\
89 cmpl $GMON_PROF_OFF,_gmonparam+GM_STATE \n\
92 # The caller's stack frame has already been built, so \n\
93 # %rbp is the caller's frame pointer. The caller's \n\
94 # raddr is in the caller's frame following the caller's \n\
95 # caller's frame pointer. \n\
104 movq 8(%rbp),%rdi \n\
107 # Our raddr is the caller's pc. \n\
109 movq 7*8(%rsp),%rsi \n\
125 #else /* !__GNUCLIKE_ASM */
126 #error "this file needs to be ported to your compiler"
127 #endif /* __GNUCLIKE_ASM */
131 * [.]mexitcount saves the return register(s), loads selfpc and calls
132 * mexitcount(selfpc) to do the work. Someday it should be in a machine
133 * dependent file together with cputime(), __mcount and [.]mcount. cputime()
134 * can't just be put in machdep.c because it has to be compiled without -pg.
136 #ifdef __GNUCLIKE_ASM
140 # Dummy label to be seen when gprof -u hides [.]mexitcount. \n\
143 .globl __mexitcount \n\
144 .type __mexitcount,@function \n\
148 GMON_PROF_HIRES = 4 \n\
151 .globl .mexitcount \n\
153 cmpl $GMON_PROF_HIRES,_gmonparam+GM_STATE \n\
154 jne .mexitcount_exit \n\
162 movq 7*8(%rsp),%rdi \n\
174 .mexitcount_exit: \n\
177 #endif /* __GNUCLIKE_ASM */
180 * Return the time elapsed since the last call. The units are machine-
189 static u_int prev_count;
191 if (cputime_clock == CPUTIME_CLOCK_TSC) {
193 * Scale the TSC a little to make cputime()'s frequency
194 * fit in an int, assuming that the TSC frequency fits
195 * in a u_int. Use a fixed scale since dynamic scaling
196 * would be slower and we can't really use the low bit
199 count = (u_int)rdtsc() & ~1u;
200 delta = (int)(count - prev_count) >> 1;
206 * Read the current value of the 8254 timer counter 0.
208 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
209 low = inb(TIMER_CNTR0);
210 high = inb(TIMER_CNTR0);
211 count = ((high << 8) | low) << CPUTIME_CLOCK_I8254_SHIFT;
214 * The timer counts down from TIMER_CNTR0_MAX to 0 and then resets.
215 * While profiling is enabled, this routine is called at least twice
216 * per timer reset (for mcounting and mexitcounting hardclock()),
217 * so at most one reset has occurred since the last call, and one
218 * has occurred iff the current count is larger than the previous
219 * count. This allows counter underflow to be detected faster
220 * than in microtime().
222 delta = prev_count - count;
224 if ((int) delta <= 0)
225 return (delta + (i8254_max_count << CPUTIME_CLOCK_I8254_SHIFT));
230 sysctl_machdep_cputime_clock(SYSCTL_HANDLER_ARGS)
235 clock = cputime_clock;
236 error = sysctl_handle_opaque(oidp, &clock, sizeof clock, req);
237 if (error == 0 && req->newptr != NULL) {
238 if (clock < 0 || clock > CPUTIME_CLOCK_TSC)
240 cputime_clock = clock;
245 SYSCTL_PROC(_machdep, OID_AUTO, cputime_clock, CTLTYPE_INT | CTLFLAG_RW,
246 0, sizeof(u_int), sysctl_machdep_cputime_clock, "I", "");
249 * The start and stop routines need not be here since we turn off profiling
250 * before calling them. They are here for convenience.
255 struct gmonparam *gp;
259 freq = atomic_load_acq_64(&tsc_freq);
260 if (cputime_clock == CPUTIME_CLOCK_UNINITIALIZED) {
261 if (freq != 0 && mp_ncpus == 1)
262 cputime_clock = CPUTIME_CLOCK_TSC;
264 cputime_clock = CPUTIME_CLOCK_I8254;
266 if (cputime_clock == CPUTIME_CLOCK_TSC) {
267 gp->profrate = freq >> 1;
268 cputime_prof_active = 1;
270 gp->profrate = i8254_freq << CPUTIME_CLOCK_I8254_SHIFT;
277 struct gmonparam *gp;
279 if (cputime_clock == CPUTIME_CLOCK_TSC)
280 cputime_prof_active = 0;
283 /* If the cpu frequency changed while profiling, report a warning. */
285 tsc_freq_changed(void *arg, const struct cf_level *level, int status)
289 * If there was an error during the transition or
290 * TSC is P-state invariant, don't do anything.
292 if (status != 0 || tsc_is_invariant)
294 if (cputime_prof_active && cputime_clock == CPUTIME_CLOCK_TSC)
295 printf("warning: cpu freq changed while profiling active\n");
298 EVENTHANDLER_DEFINE(cpufreq_post_change, tsc_freq_changed, NULL,
299 EVENTHANDLER_PRI_ANY);