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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 $
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/sysproto.h>
40 #include <sys/kernel.h>
42 #include <sys/resourcevar.h>
43 #include <sys/sysctl.h>
45 #include <sys/thread2.h>
46 #include <sys/mplock2.h>
48 #include <machine/cpu.h>
51 #include <sys/malloc.h>
55 static MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer");
57 static void kmstartup (void *);
58 SYSINIT(kmem, SI_SUB_KPROF, SI_ORDER_FIRST, kmstartup, NULL)
60 struct gmonparam _gmonparam = { GMON_PROF_OFF };
63 #include <machine/asmacros.h>
66 nullfunc_loop_profiled(void)
70 for (i = 0; i < CALIB_SCALE; i++)
74 #define nullfunc_loop_profiled_end nullfunc_profiled /* XXX */
77 nullfunc_profiled(void)
83 kmstartup(void *dummy)
86 struct gmonparam *p = &_gmonparam;
92 int mexitcount_overhead;
93 int nullfunc_loop_overhead;
94 int nullfunc_loop_profiled_time;
99 * Round lowpc and highpc to multiples of the density we're using
100 * so the rest of the scaling (here and in gprof) stays in ints.
102 p->lowpc = ROUNDDOWN((u_long)btext, HISTFRACTION * sizeof(HISTCOUNTER));
103 p->highpc = ROUNDUP((u_long)etext, HISTFRACTION * sizeof(HISTCOUNTER));
104 p->textsize = p->highpc - p->lowpc;
105 kprintf("Profiling kernel, textsize=%lu [%x..%x]\n",
106 p->textsize, p->lowpc, p->highpc);
107 p->kcountsize = p->textsize / HISTFRACTION;
108 p->hashfraction = HASHFRACTION;
109 p->fromssize = p->textsize / HASHFRACTION;
110 p->tolimit = p->textsize * ARCDENSITY / 100;
111 if (p->tolimit < MINARCS)
112 p->tolimit = MINARCS;
113 else if (p->tolimit > MAXARCS)
114 p->tolimit = MAXARCS;
115 p->tossize = p->tolimit * sizeof(struct tostruct);
116 cp = (char *)kmalloc(p->kcountsize + p->fromssize + p->tossize,
117 M_GPROF, M_NOWAIT | M_ZERO);
119 kprintf("No memory for profiling.\n");
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 kprintf("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 lwkt_gettoken(&proc0.p_token);
300 if (state == GMON_PROF_OFF) {
302 stopprofclock(&proc0);
304 } else if (state == GMON_PROF_ON) {
305 gp->state = GMON_PROF_OFF;
307 gp->profrate = profhz;
308 startprofclock(&proc0);
311 } else if (state == GMON_PROF_HIRES) {
312 gp->state = GMON_PROF_OFF;
313 stopprofclock(&proc0);
317 } else if (state != gp->state) {
320 lwkt_reltoken(&proc0.p_token);
323 return (sysctl_handle_opaque(oidp,
324 gp->kcount, gp->kcountsize, req));
326 return (sysctl_handle_opaque(oidp,
327 gp->froms, gp->fromssize, req));
329 return (sysctl_handle_opaque(oidp,
330 gp->tos, gp->tossize, req));
331 case GPROF_GMONPARAM:
332 return (sysctl_handle_opaque(oidp, gp, sizeof *gp, req));
339 SYSCTL_NODE(_kern, KERN_PROF, prof, CTLFLAG_RW, sysctl_kern_prof, "");
343 * Profiling system call.
345 * The scale factor is a fixed point number with 16 bits of fraction, so that
346 * 1.0 is represented as 0x10000. A scale factor of 0 turns off profiling.
351 sys_profil(struct profil_args *uap)
353 struct proc *p = curproc;
356 if (uap->scale > (1 << 16))
359 if (uap->scale == 0) {
364 /* Block profile interrupts while changing state. */
366 upp->pr_off = uap->offset;
367 upp->pr_scale = uap->scale;
368 upp->pr_base = uap->samples;
369 upp->pr_size = uap->size;
378 * Scale is a fixed-point number with the binary point 16 bits
379 * into the value, and is <= 1.0. pc is at most 32 bits, so the
380 * intermediate result is at most 48 bits.
382 #define PC_TO_INDEX(pc, prof) \
383 ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \
384 (u_quad_t)((prof)->pr_scale)) >> 16) & ~1)
387 * Collect user-level profiling statistics; called on a profiling tick,
388 * when a process is running in user-mode. This routine may be called
389 * from an interrupt context. We try to update the user profiling buffers
390 * cheaply with fuswintr() and suswintr(). If that fails, we revert to
391 * an AST that will vector us to trap() with a context in which copyin
392 * and copyout will work. Trap will then call addupc_task().
394 * XXX fuswintr() and suswintr() never worked (always returnde -1), remove
395 * them. It's just a bad idea to try to do this from a hard interrupt.
397 * Note that we may (rarely) not get around to the AST soon enough, and
398 * lose profile ticks when the next tick overwrites this one, but in this
399 * case the system is overloaded and the profile is probably already
403 addupc_intr(struct proc *p, u_long pc, u_int ticks)
411 if (pc < prof->pr_off ||
412 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
413 return; /* out of range; ignore */
416 prof->pr_ticks = ticks;
421 * Much like before, but we can afford to take faults here. If the
422 * update fails, we simply turn off profiling.
425 addupc_task(struct proc *p, u_long pc, u_int ticks)
432 /* Testing P_PROFIL may be unnecessary, but is certainly safe. */
433 if ((p->p_flags & P_PROFIL) == 0 || ticks == 0)
437 if (pc < prof->pr_off ||
438 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
441 addr = prof->pr_base + i;
442 if (copyin(addr, (caddr_t)&v, sizeof(v)) == 0) {
444 if (copyout((caddr_t)&v, addr, sizeof(v)) == 0)