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33 * @(#)subr_prof.c 8.3 (Berkeley) 9/23/93
34 * $FreeBSD: src/sys/kern/subr_prof.c,v 1.32.2.2 2000/08/03 00:09:32 ps Exp $
35 * $DragonFly: src/sys/kern/subr_prof.c,v 1.9 2004/06/01 22:19:30 dillon Exp $
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/sysproto.h>
41 #include <sys/kernel.h>
43 #include <sys/resourcevar.h>
44 #include <sys/sysctl.h>
46 #include <machine/ipl.h>
47 #include <machine/cpu.h>
50 #include <sys/malloc.h>
54 static MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer");
56 static void kmstartup (void *);
57 SYSINIT(kmem, SI_SUB_KPROF, SI_ORDER_FIRST, kmstartup, NULL)
59 struct gmonparam _gmonparam = { GMON_PROF_OFF };
62 #include <machine/asmacros.h>
65 nullfunc_loop_profiled()
69 for (i = 0; i < CALIB_SCALE; i++)
73 #define nullfunc_loop_profiled_end nullfunc_profiled /* XXX */
82 kmstartup(void *dummy)
85 struct gmonparam *p = &_gmonparam;
91 int mexitcount_overhead;
92 int nullfunc_loop_overhead;
93 int nullfunc_loop_profiled_time;
98 * Round lowpc and highpc to multiples of the density we're using
99 * so the rest of the scaling (here and in gprof) stays in ints.
101 p->lowpc = ROUNDDOWN((u_long)btext, HISTFRACTION * sizeof(HISTCOUNTER));
102 p->highpc = ROUNDUP((u_long)etext, HISTFRACTION * sizeof(HISTCOUNTER));
103 p->textsize = p->highpc - p->lowpc;
104 printf("Profiling kernel, textsize=%lu [%x..%x]\n",
105 p->textsize, p->lowpc, p->highpc);
106 p->kcountsize = p->textsize / HISTFRACTION;
107 p->hashfraction = HASHFRACTION;
108 p->fromssize = p->textsize / HASHFRACTION;
109 p->tolimit = p->textsize * ARCDENSITY / 100;
110 if (p->tolimit < MINARCS)
111 p->tolimit = MINARCS;
112 else if (p->tolimit > MAXARCS)
113 p->tolimit = MAXARCS;
114 p->tossize = p->tolimit * sizeof(struct tostruct);
115 cp = (char *)malloc(p->kcountsize + p->fromssize + p->tossize,
118 printf("No memory for profiling.\n");
121 bzero(cp, p->kcountsize + p->tossize + p->fromssize);
122 p->tos = (struct tostruct *)cp;
124 p->kcount = (HISTCOUNTER *)cp;
126 p->froms = (u_short *)cp;
129 /* Initialize pointers to overhead counters. */
130 p->cputime_count = &KCOUNT(p, PC_TO_I(p, cputime));
131 p->mcount_count = &KCOUNT(p, PC_TO_I(p, mcount));
132 p->mexitcount_count = &KCOUNT(p, PC_TO_I(p, mexitcount));
135 * Disable interrupts to avoid interference while we calibrate
141 * Determine overheads.
142 * XXX this needs to be repeated for each useful timer/counter.
144 cputime_overhead = 0;
146 for (i = 0; i < CALIB_SCALE; i++)
147 cputime_overhead += cputime();
152 empty_loop_time = cputime();
154 nullfunc_loop_profiled();
157 * Start profiling. There won't be any normal function calls since
158 * interrupts are disabled, but we will call the profiling routines
159 * directly to determine their overheads.
161 p->state = GMON_PROF_HIRES;
164 nullfunc_loop_profiled();
167 for (i = 0; i < CALIB_SCALE; i++)
168 #if defined(__i386__) && __GNUC__ >= 2
169 __asm("pushl %0; call __mcount; popl %%ecx"
172 : "ax", "bx", "cx", "dx", "memory");
176 mcount_overhead = KCOUNT(p, PC_TO_I(p, profil));
179 for (i = 0; i < CALIB_SCALE; i++)
180 #if defined(__i386__) && __GNUC__ >= 2
181 __asm("call " __XSTRING(HIDENAME(mexitcount)) "; 1:"
182 : : : "ax", "bx", "cx", "dx", "memory");
183 __asm("movl $1b,%0" : "=rm" (tmp_addr));
187 mexitcount_overhead = KCOUNT(p, PC_TO_I(p, tmp_addr));
189 p->state = GMON_PROF_OFF;
194 nullfunc_loop_profiled_time = 0;
195 for (tmp_addr = (uintfptr_t)nullfunc_loop_profiled;
196 tmp_addr < (uintfptr_t)nullfunc_loop_profiled_end;
197 tmp_addr += HISTFRACTION * sizeof(HISTCOUNTER))
198 nullfunc_loop_profiled_time += KCOUNT(p, PC_TO_I(p, tmp_addr));
199 #define CALIB_DOSCALE(count) (((count) + CALIB_SCALE / 3) / CALIB_SCALE)
200 #define c2n(count, freq) ((int)((count) * 1000000000LL / freq))
201 printf("cputime %d, empty_loop %d, nullfunc_loop_profiled %d, mcount %d, mexitcount %d\n",
202 CALIB_DOSCALE(c2n(cputime_overhead, p->profrate)),
203 CALIB_DOSCALE(c2n(empty_loop_time, p->profrate)),
204 CALIB_DOSCALE(c2n(nullfunc_loop_profiled_time, p->profrate)),
205 CALIB_DOSCALE(c2n(mcount_overhead, p->profrate)),
206 CALIB_DOSCALE(c2n(mexitcount_overhead, p->profrate)));
207 cputime_overhead -= empty_loop_time;
208 mcount_overhead -= empty_loop_time;
209 mexitcount_overhead -= empty_loop_time;
212 * Profiling overheads are determined by the times between the
214 * MC1: mcount() is called
215 * MC2: cputime() (called from mcount()) latches the timer
216 * MC3: mcount() completes
217 * ME1: mexitcount() is called
218 * ME2: cputime() (called from mexitcount()) latches the timer
219 * ME3: mexitcount() completes.
220 * The times between the events vary slightly depending on instruction
221 * combination and cache misses, etc. Attempt to determine the
222 * minimum times. These can be subtracted from the profiling times
223 * without much risk of reducing the profiling times below what they
224 * would be when profiling is not configured. Abbreviate:
225 * ab = minimum time between MC1 and MC3
226 * a = minumum time between MC1 and MC2
227 * b = minimum time between MC2 and MC3
228 * cd = minimum time between ME1 and ME3
229 * c = minimum time between ME1 and ME2
230 * d = minimum time between ME2 and ME3.
231 * These satisfy the relations:
232 * ab <= mcount_overhead (just measured)
234 * cd <= mexitcount_overhead (just measured)
236 * a + d <= nullfunc_loop_profiled_time (just measured)
237 * a >= 0, b >= 0, c >= 0, d >= 0.
238 * Assume that ab and cd are equal to the minimums.
240 p->cputime_overhead = CALIB_DOSCALE(cputime_overhead);
241 p->mcount_overhead = CALIB_DOSCALE(mcount_overhead - cputime_overhead);
242 p->mexitcount_overhead = CALIB_DOSCALE(mexitcount_overhead
244 nullfunc_loop_overhead = nullfunc_loop_profiled_time - empty_loop_time;
245 p->mexitcount_post_overhead = CALIB_DOSCALE((mcount_overhead
246 - nullfunc_loop_overhead)
248 p->mexitcount_pre_overhead = p->mexitcount_overhead
249 + p->cputime_overhead
250 - p->mexitcount_post_overhead;
251 p->mcount_pre_overhead = CALIB_DOSCALE(nullfunc_loop_overhead)
252 - p->mexitcount_post_overhead;
253 p->mcount_post_overhead = p->mcount_overhead
254 + p->cputime_overhead
255 - p->mcount_pre_overhead;
257 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d nsec\n",
258 c2n(p->cputime_overhead, p->profrate),
259 c2n(p->mcount_overhead, p->profrate),
260 c2n(p->mcount_pre_overhead, p->profrate),
261 c2n(p->mcount_post_overhead, p->profrate),
262 c2n(p->cputime_overhead, p->profrate),
263 c2n(p->mexitcount_overhead, p->profrate),
264 c2n(p->mexitcount_pre_overhead, p->profrate),
265 c2n(p->mexitcount_post_overhead, p->profrate));
267 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d cycles\n",
268 p->cputime_overhead, p->mcount_overhead,
269 p->mcount_pre_overhead, p->mcount_post_overhead,
270 p->cputime_overhead, p->mexitcount_overhead,
271 p->mexitcount_pre_overhead, p->mexitcount_post_overhead);
276 * Return kernel profiling information.
279 sysctl_kern_prof(SYSCTL_HANDLER_ARGS)
281 int *name = (int *) arg1;
282 u_int namelen = arg2;
283 struct gmonparam *gp = &_gmonparam;
287 /* all sysctl names at this level are terminal */
289 return (ENOTDIR); /* overloaded */
294 error = sysctl_handle_int(oidp, &state, 0, req);
299 if (state == GMON_PROF_OFF) {
301 stopprofclock(&proc0);
303 } else if (state == GMON_PROF_ON) {
304 gp->state = GMON_PROF_OFF;
306 gp->profrate = profhz;
307 startprofclock(&proc0);
310 } else if (state == GMON_PROF_HIRES) {
311 gp->state = GMON_PROF_OFF;
312 stopprofclock(&proc0);
316 } else if (state != gp->state)
320 return (sysctl_handle_opaque(oidp,
321 gp->kcount, gp->kcountsize, req));
323 return (sysctl_handle_opaque(oidp,
324 gp->froms, gp->fromssize, req));
326 return (sysctl_handle_opaque(oidp,
327 gp->tos, gp->tossize, req));
328 case GPROF_GMONPARAM:
329 return (sysctl_handle_opaque(oidp, gp, sizeof *gp, req));
336 SYSCTL_NODE(_kern, KERN_PROF, prof, CTLFLAG_RW, sysctl_kern_prof, "");
340 * Profiling system call.
342 * The scale factor is a fixed point number with 16 bits of fraction, so that
343 * 1.0 is represented as 0x10000. A scale factor of 0 turns off profiling.
347 profil(struct profil_args *uap)
349 struct proc *p = curproc;
353 if (uap->scale > (1 << 16))
355 if (uap->scale == 0) {
359 upp = &p->p_stats->p_prof;
361 /* Block profile interrupts while changing state. */
363 upp->pr_off = uap->offset;
364 upp->pr_scale = uap->scale;
365 upp->pr_base = uap->samples;
366 upp->pr_size = uap->size;
374 * Scale is a fixed-point number with the binary point 16 bits
375 * into the value, and is <= 1.0. pc is at most 32 bits, so the
376 * intermediate result is at most 48 bits.
378 #define PC_TO_INDEX(pc, prof) \
379 ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \
380 (u_quad_t)((prof)->pr_scale)) >> 16) & ~1)
383 * Collect user-level profiling statistics; called on a profiling tick,
384 * when a process is running in user-mode. This routine may be called
385 * from an interrupt context. We try to update the user profiling buffers
386 * cheaply with fuswintr() and suswintr(). If that fails, we revert to
387 * an AST that will vector us to trap() with a context in which copyin
388 * and copyout will work. Trap will then call addupc_task().
390 * Note that we may (rarely) not get around to the AST soon enough, and
391 * lose profile ticks when the next tick overwrites this one, but in this
392 * case the system is overloaded and the profile is probably already
396 addupc_intr(struct proc *p, u_long pc, u_int ticks)
405 prof = &p->p_stats->p_prof;
406 if (pc < prof->pr_off ||
407 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
408 return; /* out of range; ignore */
410 addr = prof->pr_base + i;
411 if ((v = fuswintr(addr)) == -1 || suswintr(addr, v + ticks) == -1) {
413 prof->pr_ticks = ticks;
419 * Much like before, but we can afford to take faults here. If the
420 * update fails, we simply turn off profiling.
423 addupc_task(struct proc *p, u_long pc, u_int ticks)
430 /* Testing P_PROFIL may be unnecessary, but is certainly safe. */
431 if ((p->p_flag & P_PROFIL) == 0 || ticks == 0)
434 prof = &p->p_stats->p_prof;
435 if (pc < prof->pr_off ||
436 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
439 addr = prof->pr_base + i;
440 if (copyin(addr, (caddr_t)&v, sizeof(v)) == 0) {
442 if (copyout((caddr_t)&v, addr, sizeof(v)) == 0)