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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 1.16 2007/01/06 03:23:18 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 <sys/thread2.h>
47 #include <sys/mplock2.h>
49 #include <machine/cpu.h>
52 #include <sys/malloc.h>
56 static MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer");
58 static void kmstartup (void *);
59 SYSINIT(kmem, SI_SUB_KPROF, SI_ORDER_FIRST, kmstartup, NULL)
61 struct gmonparam _gmonparam = { GMON_PROF_OFF };
64 #include <machine/asmacros.h>
67 nullfunc_loop_profiled(void)
71 for (i = 0; i < CALIB_SCALE; i++)
75 #define nullfunc_loop_profiled_end nullfunc_profiled /* XXX */
78 nullfunc_profiled(void)
84 kmstartup(void *dummy)
87 struct gmonparam *p = &_gmonparam;
93 int mexitcount_overhead;
94 int nullfunc_loop_overhead;
95 int nullfunc_loop_profiled_time;
100 * Round lowpc and highpc to multiples of the density we're using
101 * so the rest of the scaling (here and in gprof) stays in ints.
103 p->lowpc = ROUNDDOWN((u_long)btext, HISTFRACTION * sizeof(HISTCOUNTER));
104 p->highpc = ROUNDUP((u_long)etext, HISTFRACTION * sizeof(HISTCOUNTER));
105 p->textsize = p->highpc - p->lowpc;
106 kprintf("Profiling kernel, textsize=%lu [%x..%x]\n",
107 p->textsize, p->lowpc, p->highpc);
108 p->kcountsize = p->textsize / HISTFRACTION;
109 p->hashfraction = HASHFRACTION;
110 p->fromssize = p->textsize / HASHFRACTION;
111 p->tolimit = p->textsize * ARCDENSITY / 100;
112 if (p->tolimit < MINARCS)
113 p->tolimit = MINARCS;
114 else if (p->tolimit > MAXARCS)
115 p->tolimit = MAXARCS;
116 p->tossize = p->tolimit * sizeof(struct tostruct);
117 cp = (char *)kmalloc(p->kcountsize + p->fromssize + p->tossize,
120 kprintf("No memory for profiling.\n");
123 bzero(cp, p->kcountsize + p->tossize + p->fromssize);
124 p->tos = (struct tostruct *)cp;
126 p->kcount = (HISTCOUNTER *)cp;
128 p->froms = (u_short *)cp;
131 /* Initialize pointers to overhead counters. */
132 p->cputime_count = &KCOUNT(p, PC_TO_I(p, cputime));
133 p->mcount_count = &KCOUNT(p, PC_TO_I(p, mcount));
134 p->mexitcount_count = &KCOUNT(p, PC_TO_I(p, mexitcount));
137 * Disable interrupts to avoid interference while we calibrate
143 * Determine overheads.
144 * XXX this needs to be repeated for each useful timer/counter.
146 cputime_overhead = 0;
148 for (i = 0; i < CALIB_SCALE; i++)
149 cputime_overhead += cputime();
154 empty_loop_time = cputime();
156 nullfunc_loop_profiled();
159 * Start profiling. There won't be any normal function calls since
160 * interrupts are disabled, but we will call the profiling routines
161 * directly to determine their overheads.
163 p->state = GMON_PROF_HIRES;
166 nullfunc_loop_profiled();
169 for (i = 0; i < CALIB_SCALE; i++)
170 #if defined(__i386__) && __GNUC__ >= 2
171 __asm("pushl %0; call __mcount; popl %%ecx"
174 : "ax", "bx", "cx", "dx", "memory");
178 mcount_overhead = KCOUNT(p, PC_TO_I(p, profil));
181 for (i = 0; i < CALIB_SCALE; i++)
182 #if defined(__i386__) && __GNUC__ >= 2
183 __asm("call " __XSTRING(HIDENAME(mexitcount)) "; 1:"
184 : : : "ax", "bx", "cx", "dx", "memory");
185 __asm("movl $1b,%0" : "=rm" (tmp_addr));
189 mexitcount_overhead = KCOUNT(p, PC_TO_I(p, tmp_addr));
191 p->state = GMON_PROF_OFF;
196 nullfunc_loop_profiled_time = 0;
197 for (tmp_addr = (uintfptr_t)nullfunc_loop_profiled;
198 tmp_addr < (uintfptr_t)nullfunc_loop_profiled_end;
199 tmp_addr += HISTFRACTION * sizeof(HISTCOUNTER))
200 nullfunc_loop_profiled_time += KCOUNT(p, PC_TO_I(p, tmp_addr));
201 #define CALIB_DOSCALE(count) (((count) + CALIB_SCALE / 3) / CALIB_SCALE)
202 #define c2n(count, freq) ((int)((count) * 1000000000LL / freq))
203 kprintf("cputime %d, empty_loop %d, nullfunc_loop_profiled %d, mcount %d, mexitcount %d\n",
204 CALIB_DOSCALE(c2n(cputime_overhead, p->profrate)),
205 CALIB_DOSCALE(c2n(empty_loop_time, p->profrate)),
206 CALIB_DOSCALE(c2n(nullfunc_loop_profiled_time, p->profrate)),
207 CALIB_DOSCALE(c2n(mcount_overhead, p->profrate)),
208 CALIB_DOSCALE(c2n(mexitcount_overhead, p->profrate)));
209 cputime_overhead -= empty_loop_time;
210 mcount_overhead -= empty_loop_time;
211 mexitcount_overhead -= empty_loop_time;
214 * Profiling overheads are determined by the times between the
216 * MC1: mcount() is called
217 * MC2: cputime() (called from mcount()) latches the timer
218 * MC3: mcount() completes
219 * ME1: mexitcount() is called
220 * ME2: cputime() (called from mexitcount()) latches the timer
221 * ME3: mexitcount() completes.
222 * The times between the events vary slightly depending on instruction
223 * combination and cache misses, etc. Attempt to determine the
224 * minimum times. These can be subtracted from the profiling times
225 * without much risk of reducing the profiling times below what they
226 * would be when profiling is not configured. Abbreviate:
227 * ab = minimum time between MC1 and MC3
228 * a = minumum time between MC1 and MC2
229 * b = minimum time between MC2 and MC3
230 * cd = minimum time between ME1 and ME3
231 * c = minimum time between ME1 and ME2
232 * d = minimum time between ME2 and ME3.
233 * These satisfy the relations:
234 * ab <= mcount_overhead (just measured)
236 * cd <= mexitcount_overhead (just measured)
238 * a + d <= nullfunc_loop_profiled_time (just measured)
239 * a >= 0, b >= 0, c >= 0, d >= 0.
240 * Assume that ab and cd are equal to the minimums.
242 p->cputime_overhead = CALIB_DOSCALE(cputime_overhead);
243 p->mcount_overhead = CALIB_DOSCALE(mcount_overhead - cputime_overhead);
244 p->mexitcount_overhead = CALIB_DOSCALE(mexitcount_overhead
246 nullfunc_loop_overhead = nullfunc_loop_profiled_time - empty_loop_time;
247 p->mexitcount_post_overhead = CALIB_DOSCALE((mcount_overhead
248 - nullfunc_loop_overhead)
250 p->mexitcount_pre_overhead = p->mexitcount_overhead
251 + p->cputime_overhead
252 - p->mexitcount_post_overhead;
253 p->mcount_pre_overhead = CALIB_DOSCALE(nullfunc_loop_overhead)
254 - p->mexitcount_post_overhead;
255 p->mcount_post_overhead = p->mcount_overhead
256 + p->cputime_overhead
257 - p->mcount_pre_overhead;
259 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d nsec\n",
260 c2n(p->cputime_overhead, p->profrate),
261 c2n(p->mcount_overhead, p->profrate),
262 c2n(p->mcount_pre_overhead, p->profrate),
263 c2n(p->mcount_post_overhead, p->profrate),
264 c2n(p->cputime_overhead, p->profrate),
265 c2n(p->mexitcount_overhead, p->profrate),
266 c2n(p->mexitcount_pre_overhead, p->profrate),
267 c2n(p->mexitcount_post_overhead, p->profrate));
269 "Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d cycles\n",
270 p->cputime_overhead, p->mcount_overhead,
271 p->mcount_pre_overhead, p->mcount_post_overhead,
272 p->cputime_overhead, p->mexitcount_overhead,
273 p->mexitcount_pre_overhead, p->mexitcount_post_overhead);
278 * Return kernel profiling information.
281 sysctl_kern_prof(SYSCTL_HANDLER_ARGS)
283 int *name = (int *) arg1;
284 u_int namelen = arg2;
285 struct gmonparam *gp = &_gmonparam;
289 /* all sysctl names at this level are terminal */
291 return (ENOTDIR); /* overloaded */
296 error = sysctl_handle_int(oidp, &state, 0, req);
301 lwkt_gettoken(&proc0.p_token);
302 if (state == GMON_PROF_OFF) {
304 stopprofclock(&proc0);
306 } else if (state == GMON_PROF_ON) {
307 gp->state = GMON_PROF_OFF;
309 gp->profrate = profhz;
310 startprofclock(&proc0);
313 } else if (state == GMON_PROF_HIRES) {
314 gp->state = GMON_PROF_OFF;
315 stopprofclock(&proc0);
319 } else if (state != gp->state) {
322 lwkt_reltoken(&proc0.p_token);
325 return (sysctl_handle_opaque(oidp,
326 gp->kcount, gp->kcountsize, req));
328 return (sysctl_handle_opaque(oidp,
329 gp->froms, gp->fromssize, req));
331 return (sysctl_handle_opaque(oidp,
332 gp->tos, gp->tossize, req));
333 case GPROF_GMONPARAM:
334 return (sysctl_handle_opaque(oidp, gp, sizeof *gp, req));
341 SYSCTL_NODE(_kern, KERN_PROF, prof, CTLFLAG_RW, sysctl_kern_prof, "");
345 * Profiling system call.
347 * The scale factor is a fixed point number with 16 bits of fraction, so that
348 * 1.0 is represented as 0x10000. A scale factor of 0 turns off profiling.
353 sys_profil(struct profil_args *uap)
355 struct proc *p = curproc;
358 if (uap->scale > (1 << 16))
361 if (uap->scale == 0) {
366 /* Block profile interrupts while changing state. */
368 upp->pr_off = uap->offset;
369 upp->pr_scale = uap->scale;
370 upp->pr_base = uap->samples;
371 upp->pr_size = uap->size;
380 * Scale is a fixed-point number with the binary point 16 bits
381 * into the value, and is <= 1.0. pc is at most 32 bits, so the
382 * intermediate result is at most 48 bits.
384 #define PC_TO_INDEX(pc, prof) \
385 ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \
386 (u_quad_t)((prof)->pr_scale)) >> 16) & ~1)
389 * Collect user-level profiling statistics; called on a profiling tick,
390 * when a process is running in user-mode. This routine may be called
391 * from an interrupt context. We try to update the user profiling buffers
392 * cheaply with fuswintr() and suswintr(). If that fails, we revert to
393 * an AST that will vector us to trap() with a context in which copyin
394 * and copyout will work. Trap will then call addupc_task().
396 * XXX fuswintr() and suswintr() never worked (always returnde -1), remove
397 * them. It's just a bad idea to try to do this from a hard interrupt.
399 * Note that we may (rarely) not get around to the AST soon enough, and
400 * lose profile ticks when the next tick overwrites this one, but in this
401 * case the system is overloaded and the profile is probably already
405 addupc_intr(struct proc *p, u_long pc, u_int ticks)
414 if (pc < prof->pr_off ||
415 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
416 return; /* out of range; ignore */
418 addr = prof->pr_base + i;
420 prof->pr_ticks = ticks;
425 * Much like before, but we can afford to take faults here. If the
426 * update fails, we simply turn off profiling.
429 addupc_task(struct proc *p, u_long pc, u_int ticks)
436 /* Testing P_PROFIL may be unnecessary, but is certainly safe. */
437 if ((p->p_flag & P_PROFIL) == 0 || ticks == 0)
441 if (pc < prof->pr_off ||
442 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
445 addr = prof->pr_base + i;
446 if (copyin(addr, (caddr_t)&v, sizeof(v)) == 0) {
448 if (copyout((caddr_t)&v, addr, sizeof(v)) == 0)