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| Current File : //sys/kern/subr_prof.c |
/*-
* Copyright (c) 1982, 1986, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)subr_prof.c 8.3 (Berkeley) 9/23/93
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/kern/subr_prof.c 225617 2011-09-16 13:58:51Z kmacy $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sysctl.h>
#include <machine/cpu.h>
#ifdef GPROF
#include <sys/malloc.h>
#include <sys/gmon.h>
#undef MCOUNT
static MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer");
static void kmstartup(void *);
SYSINIT(kmem, SI_SUB_KPROF, SI_ORDER_FIRST, kmstartup, NULL);
struct gmonparam _gmonparam = { GMON_PROF_OFF };
#ifdef GUPROF
void
nullfunc_loop_profiled()
{
int i;
for (i = 0; i < CALIB_SCALE; i++)
nullfunc_profiled();
}
#define nullfunc_loop_profiled_end nullfunc_profiled /* XXX */
void
nullfunc_profiled()
{
}
#endif /* GUPROF */
/*
* Update the histograms to support extending the text region arbitrarily.
* This is done slightly naively (no sparse regions), so will waste slight
* amounts of memory, but will overall work nicely enough to allow profiling
* of KLDs.
*/
void
kmupetext(uintfptr_t nhighpc)
{
struct gmonparam np; /* slightly large */
struct gmonparam *p = &_gmonparam;
char *cp;
GIANT_REQUIRED;
bcopy(p, &np, sizeof(*p));
np.highpc = ROUNDUP(nhighpc, HISTFRACTION * sizeof(HISTCOUNTER));
if (np.highpc <= p->highpc)
return;
np.textsize = np.highpc - p->lowpc;
np.kcountsize = np.textsize / HISTFRACTION;
np.hashfraction = HASHFRACTION;
np.fromssize = np.textsize / HASHFRACTION;
np.tolimit = np.textsize * ARCDENSITY / 100;
if (np.tolimit < MINARCS)
np.tolimit = MINARCS;
else if (np.tolimit > MAXARCS)
np.tolimit = MAXARCS;
np.tossize = np.tolimit * sizeof(struct tostruct);
cp = malloc(np.kcountsize + np.fromssize + np.tossize,
M_GPROF, M_WAITOK);
/*
* Check for something else extending highpc while we slept.
*/
if (np.highpc <= p->highpc) {
free(cp, M_GPROF);
return;
}
np.tos = (struct tostruct *)cp;
cp += np.tossize;
np.kcount = (HISTCOUNTER *)cp;
cp += np.kcountsize;
np.froms = (u_short *)cp;
#ifdef GUPROF
/* Reinitialize pointers to overhead counters. */
np.cputime_count = &KCOUNT(&np, PC_TO_I(&np, cputime));
np.mcount_count = &KCOUNT(&np, PC_TO_I(&np, mcount));
np.mexitcount_count = &KCOUNT(&np, PC_TO_I(&np, mexitcount));
#endif
critical_enter();
bcopy(p->tos, np.tos, p->tossize);
bzero((char *)np.tos + p->tossize, np.tossize - p->tossize);
bcopy(p->kcount, np.kcount, p->kcountsize);
bzero((char *)np.kcount + p->kcountsize, np.kcountsize -
p->kcountsize);
bcopy(p->froms, np.froms, p->fromssize);
bzero((char *)np.froms + p->fromssize, np.fromssize - p->fromssize);
cp = (char *)p->tos;
bcopy(&np, p, sizeof(*p));
critical_exit();
free(cp, M_GPROF);
}
static void
kmstartup(dummy)
void *dummy;
{
char *cp;
struct gmonparam *p = &_gmonparam;
#ifdef GUPROF
int cputime_overhead;
int empty_loop_time;
int i;
int mcount_overhead;
int mexitcount_overhead;
int nullfunc_loop_overhead;
int nullfunc_loop_profiled_time;
uintfptr_t tmp_addr;
#endif
/*
* Round lowpc and highpc to multiples of the density we're using
* so the rest of the scaling (here and in gprof) stays in ints.
*/
p->lowpc = ROUNDDOWN((u_long)btext, HISTFRACTION * sizeof(HISTCOUNTER));
p->highpc = ROUNDUP((u_long)etext, HISTFRACTION * sizeof(HISTCOUNTER));
p->textsize = p->highpc - p->lowpc;
printf("Profiling kernel, textsize=%lu [%jx..%jx]\n",
p->textsize, (uintmax_t)p->lowpc, (uintmax_t)p->highpc);
p->kcountsize = p->textsize / HISTFRACTION;
p->hashfraction = HASHFRACTION;
p->fromssize = p->textsize / HASHFRACTION;
p->tolimit = p->textsize * ARCDENSITY / 100;
if (p->tolimit < MINARCS)
p->tolimit = MINARCS;
else if (p->tolimit > MAXARCS)
p->tolimit = MAXARCS;
p->tossize = p->tolimit * sizeof(struct tostruct);
cp = (char *)malloc(p->kcountsize + p->fromssize + p->tossize,
M_GPROF, M_WAITOK | M_ZERO);
p->tos = (struct tostruct *)cp;
cp += p->tossize;
p->kcount = (HISTCOUNTER *)cp;
cp += p->kcountsize;
p->froms = (u_short *)cp;
p->histcounter_type = FUNCTION_ALIGNMENT / HISTFRACTION * NBBY;
#ifdef GUPROF
/* Signed counters. */
p->histcounter_type = -p->histcounter_type;
/* Initialize pointers to overhead counters. */
p->cputime_count = &KCOUNT(p, PC_TO_I(p, cputime));
p->mcount_count = &KCOUNT(p, PC_TO_I(p, mcount));
p->mexitcount_count = &KCOUNT(p, PC_TO_I(p, mexitcount));
/*
* Disable interrupts to avoid interference while we calibrate
* things.
*/
critical_enter();
/*
* Determine overheads.
* XXX this needs to be repeated for each useful timer/counter.
*/
cputime_overhead = 0;
startguprof(p);
for (i = 0; i < CALIB_SCALE; i++)
cputime_overhead += cputime();
empty_loop();
startguprof(p);
empty_loop();
empty_loop_time = cputime();
nullfunc_loop_profiled();
/*
* Start profiling. There won't be any normal function calls since
* interrupts are disabled, but we will call the profiling routines
* directly to determine their overheads.
*/
p->state = GMON_PROF_HIRES;
startguprof(p);
nullfunc_loop_profiled();
startguprof(p);
for (i = 0; i < CALIB_SCALE; i++)
MCOUNT_OVERHEAD(sys_profil);
mcount_overhead = KCOUNT(p, PC_TO_I(p, sys_profil));
startguprof(p);
for (i = 0; i < CALIB_SCALE; i++)
MEXITCOUNT_OVERHEAD();
MEXITCOUNT_OVERHEAD_GETLABEL(tmp_addr);
mexitcount_overhead = KCOUNT(p, PC_TO_I(p, tmp_addr));
p->state = GMON_PROF_OFF;
stopguprof(p);
critical_exit();
nullfunc_loop_profiled_time = 0;
for (tmp_addr = (uintfptr_t)nullfunc_loop_profiled;
tmp_addr < (uintfptr_t)nullfunc_loop_profiled_end;
tmp_addr += HISTFRACTION * sizeof(HISTCOUNTER))
nullfunc_loop_profiled_time += KCOUNT(p, PC_TO_I(p, tmp_addr));
#define CALIB_DOSCALE(count) (((count) + CALIB_SCALE / 3) / CALIB_SCALE)
#define c2n(count, freq) ((int)((count) * 1000000000LL / freq))
printf("cputime %d, empty_loop %d, nullfunc_loop_profiled %d, mcount %d, mexitcount %d\n",
CALIB_DOSCALE(c2n(cputime_overhead, p->profrate)),
CALIB_DOSCALE(c2n(empty_loop_time, p->profrate)),
CALIB_DOSCALE(c2n(nullfunc_loop_profiled_time, p->profrate)),
CALIB_DOSCALE(c2n(mcount_overhead, p->profrate)),
CALIB_DOSCALE(c2n(mexitcount_overhead, p->profrate)));
cputime_overhead -= empty_loop_time;
mcount_overhead -= empty_loop_time;
mexitcount_overhead -= empty_loop_time;
/*-
* Profiling overheads are determined by the times between the
* following events:
* MC1: mcount() is called
* MC2: cputime() (called from mcount()) latches the timer
* MC3: mcount() completes
* ME1: mexitcount() is called
* ME2: cputime() (called from mexitcount()) latches the timer
* ME3: mexitcount() completes.
* The times between the events vary slightly depending on instruction
* combination and cache misses, etc. Attempt to determine the
* minimum times. These can be subtracted from the profiling times
* without much risk of reducing the profiling times below what they
* would be when profiling is not configured. Abbreviate:
* ab = minimum time between MC1 and MC3
* a = minumum time between MC1 and MC2
* b = minimum time between MC2 and MC3
* cd = minimum time between ME1 and ME3
* c = minimum time between ME1 and ME2
* d = minimum time between ME2 and ME3.
* These satisfy the relations:
* ab <= mcount_overhead (just measured)
* a + b <= ab
* cd <= mexitcount_overhead (just measured)
* c + d <= cd
* a + d <= nullfunc_loop_profiled_time (just measured)
* a >= 0, b >= 0, c >= 0, d >= 0.
* Assume that ab and cd are equal to the minimums.
*/
p->cputime_overhead = CALIB_DOSCALE(cputime_overhead);
p->mcount_overhead = CALIB_DOSCALE(mcount_overhead - cputime_overhead);
p->mexitcount_overhead = CALIB_DOSCALE(mexitcount_overhead
- cputime_overhead);
nullfunc_loop_overhead = nullfunc_loop_profiled_time - empty_loop_time;
p->mexitcount_post_overhead = CALIB_DOSCALE((mcount_overhead
- nullfunc_loop_overhead)
/ 4);
p->mexitcount_pre_overhead = p->mexitcount_overhead
+ p->cputime_overhead
- p->mexitcount_post_overhead;
p->mcount_pre_overhead = CALIB_DOSCALE(nullfunc_loop_overhead)
- p->mexitcount_post_overhead;
p->mcount_post_overhead = p->mcount_overhead
+ p->cputime_overhead
- p->mcount_pre_overhead;
printf(
"Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d nsec\n",
c2n(p->cputime_overhead, p->profrate),
c2n(p->mcount_overhead, p->profrate),
c2n(p->mcount_pre_overhead, p->profrate),
c2n(p->mcount_post_overhead, p->profrate),
c2n(p->cputime_overhead, p->profrate),
c2n(p->mexitcount_overhead, p->profrate),
c2n(p->mexitcount_pre_overhead, p->profrate),
c2n(p->mexitcount_post_overhead, p->profrate));
printf(
"Profiling overheads: mcount: %d+%d, %d+%d; mexitcount: %d+%d, %d+%d cycles\n",
p->cputime_overhead, p->mcount_overhead,
p->mcount_pre_overhead, p->mcount_post_overhead,
p->cputime_overhead, p->mexitcount_overhead,
p->mexitcount_pre_overhead, p->mexitcount_post_overhead);
#endif /* GUPROF */
}
/*
* Return kernel profiling information.
*/
static int
sysctl_kern_prof(SYSCTL_HANDLER_ARGS)
{
int *name = (int *) arg1;
u_int namelen = arg2;
struct gmonparam *gp = &_gmonparam;
int error;
int state;
/* all sysctl names at this level are terminal */
if (namelen != 1)
return (ENOTDIR); /* overloaded */
switch (name[0]) {
case GPROF_STATE:
state = gp->state;
error = sysctl_handle_int(oidp, &state, 0, req);
if (error)
return (error);
if (!req->newptr)
return (0);
if (state == GMON_PROF_OFF) {
gp->state = state;
PROC_LOCK(&proc0);
stopprofclock(&proc0);
PROC_UNLOCK(&proc0);
stopguprof(gp);
} else if (state == GMON_PROF_ON) {
gp->state = GMON_PROF_OFF;
stopguprof(gp);
gp->profrate = profhz;
PROC_LOCK(&proc0);
startprofclock(&proc0);
PROC_UNLOCK(&proc0);
gp->state = state;
#ifdef GUPROF
} else if (state == GMON_PROF_HIRES) {
gp->state = GMON_PROF_OFF;
PROC_LOCK(&proc0);
stopprofclock(&proc0);
PROC_UNLOCK(&proc0);
startguprof(gp);
gp->state = state;
#endif
} else if (state != gp->state)
return (EINVAL);
return (0);
case GPROF_COUNT:
return (sysctl_handle_opaque(oidp,
gp->kcount, gp->kcountsize, req));
case GPROF_FROMS:
return (sysctl_handle_opaque(oidp,
gp->froms, gp->fromssize, req));
case GPROF_TOS:
return (sysctl_handle_opaque(oidp,
gp->tos, gp->tossize, req));
case GPROF_GMONPARAM:
return (sysctl_handle_opaque(oidp, gp, sizeof *gp, req));
default:
return (EOPNOTSUPP);
}
/* NOTREACHED */
}
SYSCTL_NODE(_kern, KERN_PROF, prof, CTLFLAG_RW, sysctl_kern_prof, "");
#endif /* GPROF */
/*
* Profiling system call.
*
* The scale factor is a fixed point number with 16 bits of fraction, so that
* 1.0 is represented as 0x10000. A scale factor of 0 turns off profiling.
*/
#ifndef _SYS_SYSPROTO_H_
struct profil_args {
caddr_t samples;
size_t size;
size_t offset;
u_int scale;
};
#endif
/* ARGSUSED */
int
sys_profil(struct thread *td, struct profil_args *uap)
{
struct uprof *upp;
struct proc *p;
if (uap->scale > (1 << 16))
return (EINVAL);
p = td->td_proc;
if (uap->scale == 0) {
PROC_LOCK(p);
stopprofclock(p);
PROC_UNLOCK(p);
return (0);
}
PROC_LOCK(p);
upp = &td->td_proc->p_stats->p_prof;
PROC_SLOCK(p);
upp->pr_off = uap->offset;
upp->pr_scale = uap->scale;
upp->pr_base = uap->samples;
upp->pr_size = uap->size;
PROC_SUNLOCK(p);
startprofclock(p);
PROC_UNLOCK(p);
return (0);
}
/*
* Scale is a fixed-point number with the binary point 16 bits
* into the value, and is <= 1.0. pc is at most 32 bits, so the
* intermediate result is at most 48 bits.
*/
#define PC_TO_INDEX(pc, prof) \
((int)(((u_quad_t)((pc) - (prof)->pr_off) * \
(u_quad_t)((prof)->pr_scale)) >> 16) & ~1)
/*
* Collect user-level profiling statistics; called on a profiling tick,
* when a process is running in user-mode. This routine may be called
* from an interrupt context. We try to update the user profiling buffers
* cheaply with fuswintr() and suswintr(). If that fails, we revert to
* an AST that will vector us to trap() with a context in which copyin
* and copyout will work. Trap will then call addupc_task().
*
* Note that we may (rarely) not get around to the AST soon enough, and
* lose profile ticks when the next tick overwrites this one, but in this
* case the system is overloaded and the profile is probably already
* inaccurate.
*/
void
addupc_intr(struct thread *td, uintfptr_t pc, u_int ticks)
{
struct uprof *prof;
caddr_t addr;
u_int i;
int v;
if (ticks == 0)
return;
prof = &td->td_proc->p_stats->p_prof;
PROC_SLOCK(td->td_proc);
if (pc < prof->pr_off ||
(i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) {
PROC_SUNLOCK(td->td_proc);
return; /* out of range; ignore */
}
addr = prof->pr_base + i;
PROC_SUNLOCK(td->td_proc);
if ((v = fuswintr(addr)) == -1 || suswintr(addr, v + ticks) == -1) {
td->td_profil_addr = pc;
td->td_profil_ticks = ticks;
td->td_pflags |= TDP_OWEUPC;
thread_lock(td);
td->td_flags |= TDF_ASTPENDING;
thread_unlock(td);
}
}
/*
* Much like before, but we can afford to take faults here. If the
* update fails, we simply turn off profiling.
*/
void
addupc_task(struct thread *td, uintfptr_t pc, u_int ticks)
{
struct proc *p = td->td_proc;
struct uprof *prof;
caddr_t addr;
u_int i;
u_short v;
int stop = 0;
if (ticks == 0)
return;
PROC_LOCK(p);
if (!(p->p_flag & P_PROFIL)) {
PROC_UNLOCK(p);
return;
}
p->p_profthreads++;
prof = &p->p_stats->p_prof;
PROC_SLOCK(p);
if (pc < prof->pr_off ||
(i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) {
PROC_SUNLOCK(p);
goto out;
}
addr = prof->pr_base + i;
PROC_SUNLOCK(p);
PROC_UNLOCK(p);
if (copyin(addr, &v, sizeof(v)) == 0) {
v += ticks;
if (copyout(&v, addr, sizeof(v)) == 0) {
PROC_LOCK(p);
goto out;
}
}
stop = 1;
PROC_LOCK(p);
out:
if (--p->p_profthreads == 0) {
if (p->p_flag & P_STOPPROF) {
wakeup(&p->p_profthreads);
stop = 0;
}
}
if (stop)
stopprofclock(p);
PROC_UNLOCK(p);
}
#if (defined(__amd64__) || defined(__i386__)) && \
defined(__GNUCLIKE_CTOR_SECTION_HANDLING)
/*
* Support for "--test-coverage --profile-arcs" in GCC.
*
* We need to call all the functions in the .ctor section, in order
* to get all the counter-arrays strung into a list.
*
* XXX: the .ctors call __bb_init_func which is located in over in
* XXX: i386/i386/support.s for historical reasons. There is probably
* XXX: no reason for that to be assembler anymore, but doing it right
* XXX: in MI C code requires one to reverse-engineer the type-selection
* XXX: inside GCC. Have fun.
*
* XXX: Worrisome perspective: Calling the .ctors may make C++ in the
* XXX: kernel feasible. Don't.
*/
typedef void (*ctor_t)(void);
extern ctor_t _start_ctors, _stop_ctors;
static void
tcov_init(void *foo __unused)
{
ctor_t *p, q;
for (p = &_start_ctors; p < &_stop_ctors; p++) {
q = *p;
q();
}
}
SYSINIT(tcov_init, SI_SUB_KPROF, SI_ORDER_SECOND, tcov_init, NULL);
/*
* GCC contains magic to recognize calls to for instance execve() and
* puts in calls to this function to preserve the profile counters.
* XXX: Put zinging punchline here.
*/
void __bb_fork_func(void);
void
__bb_fork_func(void)
{
}
#endif