freebsd-dev/sys/kern/kern_tc.c
Robert Watson 83160d1408 By default, don't compile in counters of calls to various time
query functions in the kernel, as these effectively serialize
parallel calls to the gettimeofday(2) system call, as well as
other kernel services that use timestamps.

Use the NetBSD version of the fix (kern_tc.c:1.32 by ad@) as
they have picked up our timecounter code and also ran into the
same problem.

Reported by:	kris
Obtained from:	NetBSD
MFC after:	3 days
2009-03-08 22:19:28 +00:00

986 lines
25 KiB
C

/*-
* ----------------------------------------------------------------------------
* "THE BEER-WARE LICENSE" (Revision 42):
* <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you
* can do whatever you want with this stuff. If we meet some day, and you think
* this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
* ----------------------------------------------------------------------------
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ntp.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/systm.h>
#include <sys/timepps.h>
#include <sys/timetc.h>
#include <sys/timex.h>
/*
* A large step happens on boot. This constant detects such steps.
* It is relatively small so that ntp_update_second gets called enough
* in the typical 'missed a couple of seconds' case, but doesn't loop
* forever when the time step is large.
*/
#define LARGE_STEP 200
/*
* Implement a dummy timecounter which we can use until we get a real one
* in the air. This allows the console and other early stuff to use
* time services.
*/
static u_int
dummy_get_timecount(struct timecounter *tc)
{
static u_int now;
return (++now);
}
static struct timecounter dummy_timecounter = {
dummy_get_timecount, 0, ~0u, 1000000, "dummy", -1000000
};
struct timehands {
/* These fields must be initialized by the driver. */
struct timecounter *th_counter;
int64_t th_adjustment;
u_int64_t th_scale;
u_int th_offset_count;
struct bintime th_offset;
struct timeval th_microtime;
struct timespec th_nanotime;
/* Fields not to be copied in tc_windup start with th_generation. */
volatile u_int th_generation;
struct timehands *th_next;
};
static struct timehands th0;
static struct timehands th9 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th0};
static struct timehands th8 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th9};
static struct timehands th7 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th8};
static struct timehands th6 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th7};
static struct timehands th5 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th6};
static struct timehands th4 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th5};
static struct timehands th3 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th4};
static struct timehands th2 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th3};
static struct timehands th1 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th2};
static struct timehands th0 = {
&dummy_timecounter,
0,
(uint64_t)-1 / 1000000,
0,
{1, 0},
{0, 0},
{0, 0},
1,
&th1
};
static struct timehands *volatile timehands = &th0;
struct timecounter *timecounter = &dummy_timecounter;
static struct timecounter *timecounters = &dummy_timecounter;
time_t time_second = 1;
time_t time_uptime = 1;
static struct bintime boottimebin;
struct timeval boottime;
static int sysctl_kern_boottime(SYSCTL_HANDLER_ARGS);
SYSCTL_PROC(_kern, KERN_BOOTTIME, boottime, CTLTYPE_STRUCT|CTLFLAG_RD,
NULL, 0, sysctl_kern_boottime, "S,timeval", "System boottime");
SYSCTL_NODE(_kern, OID_AUTO, timecounter, CTLFLAG_RW, 0, "");
SYSCTL_NODE(_kern_timecounter, OID_AUTO, tc, CTLFLAG_RW, 0, "");
static int timestepwarnings;
SYSCTL_INT(_kern_timecounter, OID_AUTO, stepwarnings, CTLFLAG_RW,
&timestepwarnings, 0, "");
#ifdef TC_COUNTERS
#define TC_STATS(foo) \
static u_int foo; \
SYSCTL_UINT(_kern_timecounter, OID_AUTO, foo, CTLFLAG_RD, &foo, 0, "");\
struct __hack
TC_STATS(nbinuptime); TC_STATS(nnanouptime); TC_STATS(nmicrouptime);
TC_STATS(nbintime); TC_STATS(nnanotime); TC_STATS(nmicrotime);
TC_STATS(ngetbinuptime); TC_STATS(ngetnanouptime); TC_STATS(ngetmicrouptime);
TC_STATS(ngetbintime); TC_STATS(ngetnanotime); TC_STATS(ngetmicrotime);
TC_STATS(nsetclock);
#define TC_COUNT(var) var++
#undef TC_STATS
#else
#define TC_COUNT(var) /* nothing */
#endif /* TC_COUNTERS */
static void tc_windup(void);
static void cpu_tick_calibrate(int);
static int
sysctl_kern_boottime(SYSCTL_HANDLER_ARGS)
{
#ifdef SCTL_MASK32
int tv[2];
if (req->flags & SCTL_MASK32) {
tv[0] = boottime.tv_sec;
tv[1] = boottime.tv_usec;
return SYSCTL_OUT(req, tv, sizeof(tv));
} else
#endif
return SYSCTL_OUT(req, &boottime, sizeof(boottime));
}
static int
sysctl_kern_timecounter_get(SYSCTL_HANDLER_ARGS)
{
u_int ncount;
struct timecounter *tc = arg1;
ncount = tc->tc_get_timecount(tc);
return sysctl_handle_int(oidp, &ncount, 0, req);
}
static int
sysctl_kern_timecounter_freq(SYSCTL_HANDLER_ARGS)
{
u_int64_t freq;
struct timecounter *tc = arg1;
freq = tc->tc_frequency;
return sysctl_handle_quad(oidp, &freq, 0, req);
}
/*
* Return the difference between the timehands' counter value now and what
* was when we copied it to the timehands' offset_count.
*/
static __inline u_int
tc_delta(struct timehands *th)
{
struct timecounter *tc;
tc = th->th_counter;
return ((tc->tc_get_timecount(tc) - th->th_offset_count) &
tc->tc_counter_mask);
}
/*
* Functions for reading the time. We have to loop until we are sure that
* the timehands that we operated on was not updated under our feet. See
* the comment in <sys/time.h> for a description of these 12 functions.
*/
void
binuptime(struct bintime *bt)
{
struct timehands *th;
u_int gen;
TC_COUNT(nbinuptime);
do {
th = timehands;
gen = th->th_generation;
*bt = th->th_offset;
bintime_addx(bt, th->th_scale * tc_delta(th));
} while (gen == 0 || gen != th->th_generation);
}
void
nanouptime(struct timespec *tsp)
{
struct bintime bt;
TC_COUNT(nnanouptime);
binuptime(&bt);
bintime2timespec(&bt, tsp);
}
void
microuptime(struct timeval *tvp)
{
struct bintime bt;
TC_COUNT(nmicrouptime);
binuptime(&bt);
bintime2timeval(&bt, tvp);
}
void
bintime(struct bintime *bt)
{
TC_COUNT(nbintime);
binuptime(bt);
bintime_add(bt, &boottimebin);
}
void
nanotime(struct timespec *tsp)
{
struct bintime bt;
TC_COUNT(nnanotime);
bintime(&bt);
bintime2timespec(&bt, tsp);
}
void
microtime(struct timeval *tvp)
{
struct bintime bt;
TC_COUNT(nmicrotime);
bintime(&bt);
bintime2timeval(&bt, tvp);
}
void
getbinuptime(struct bintime *bt)
{
struct timehands *th;
u_int gen;
TC_COUNT(ngetbinuptime);
do {
th = timehands;
gen = th->th_generation;
*bt = th->th_offset;
} while (gen == 0 || gen != th->th_generation);
}
void
getnanouptime(struct timespec *tsp)
{
struct timehands *th;
u_int gen;
TC_COUNT(ngetnanouptime);
do {
th = timehands;
gen = th->th_generation;
bintime2timespec(&th->th_offset, tsp);
} while (gen == 0 || gen != th->th_generation);
}
void
getmicrouptime(struct timeval *tvp)
{
struct timehands *th;
u_int gen;
TC_COUNT(ngetmicrouptime);
do {
th = timehands;
gen = th->th_generation;
bintime2timeval(&th->th_offset, tvp);
} while (gen == 0 || gen != th->th_generation);
}
void
getbintime(struct bintime *bt)
{
struct timehands *th;
u_int gen;
TC_COUNT(ngetbintime);
do {
th = timehands;
gen = th->th_generation;
*bt = th->th_offset;
} while (gen == 0 || gen != th->th_generation);
bintime_add(bt, &boottimebin);
}
void
getnanotime(struct timespec *tsp)
{
struct timehands *th;
u_int gen;
TC_COUNT(ngetnanotime);
do {
th = timehands;
gen = th->th_generation;
*tsp = th->th_nanotime;
} while (gen == 0 || gen != th->th_generation);
}
void
getmicrotime(struct timeval *tvp)
{
struct timehands *th;
u_int gen;
TC_COUNT(ngetmicrotime);
do {
th = timehands;
gen = th->th_generation;
*tvp = th->th_microtime;
} while (gen == 0 || gen != th->th_generation);
}
/*
* Initialize a new timecounter and possibly use it.
*/
void
tc_init(struct timecounter *tc)
{
u_int u;
struct sysctl_oid *tc_root;
u = tc->tc_frequency / tc->tc_counter_mask;
/* XXX: We need some margin here, 10% is a guess */
u *= 11;
u /= 10;
if (u > hz && tc->tc_quality >= 0) {
tc->tc_quality = -2000;
if (bootverbose) {
printf("Timecounter \"%s\" frequency %ju Hz",
tc->tc_name, (uintmax_t)tc->tc_frequency);
printf(" -- Insufficient hz, needs at least %u\n", u);
}
} else if (tc->tc_quality >= 0 || bootverbose) {
printf("Timecounter \"%s\" frequency %ju Hz quality %d\n",
tc->tc_name, (uintmax_t)tc->tc_frequency,
tc->tc_quality);
}
tc->tc_next = timecounters;
timecounters = tc;
/*
* Set up sysctl tree for this counter.
*/
tc_root = SYSCTL_ADD_NODE(NULL,
SYSCTL_STATIC_CHILDREN(_kern_timecounter_tc), OID_AUTO, tc->tc_name,
CTLFLAG_RW, 0, "timecounter description");
SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
"mask", CTLFLAG_RD, &(tc->tc_counter_mask), 0,
"mask for implemented bits");
SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
"counter", CTLTYPE_UINT | CTLFLAG_RD, tc, sizeof(*tc),
sysctl_kern_timecounter_get, "IU", "current timecounter value");
SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
"frequency", CTLTYPE_QUAD | CTLFLAG_RD, tc, sizeof(*tc),
sysctl_kern_timecounter_freq, "QU", "timecounter frequency");
SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
"quality", CTLFLAG_RD, &(tc->tc_quality), 0,
"goodness of time counter");
/*
* Never automatically use a timecounter with negative quality.
* Even though we run on the dummy counter, switching here may be
* worse since this timecounter may not be monotonous.
*/
if (tc->tc_quality < 0)
return;
if (tc->tc_quality < timecounter->tc_quality)
return;
if (tc->tc_quality == timecounter->tc_quality &&
tc->tc_frequency < timecounter->tc_frequency)
return;
(void)tc->tc_get_timecount(tc);
(void)tc->tc_get_timecount(tc);
timecounter = tc;
}
/* Report the frequency of the current timecounter. */
u_int64_t
tc_getfrequency(void)
{
return (timehands->th_counter->tc_frequency);
}
/*
* Step our concept of UTC. This is done by modifying our estimate of
* when we booted.
* XXX: not locked.
*/
void
tc_setclock(struct timespec *ts)
{
struct timespec tbef, taft;
struct bintime bt, bt2;
cpu_tick_calibrate(1);
TC_COUNT(nsetclock);
nanotime(&tbef);
timespec2bintime(ts, &bt);
binuptime(&bt2);
bintime_sub(&bt, &bt2);
bintime_add(&bt2, &boottimebin);
boottimebin = bt;
bintime2timeval(&bt, &boottime);
/* XXX fiddle all the little crinkly bits around the fiords... */
tc_windup();
nanotime(&taft);
if (timestepwarnings) {
log(LOG_INFO,
"Time stepped from %jd.%09ld to %jd.%09ld (%jd.%09ld)\n",
(intmax_t)tbef.tv_sec, tbef.tv_nsec,
(intmax_t)taft.tv_sec, taft.tv_nsec,
(intmax_t)ts->tv_sec, ts->tv_nsec);
}
cpu_tick_calibrate(1);
}
/*
* Initialize the next struct timehands in the ring and make
* it the active timehands. Along the way we might switch to a different
* timecounter and/or do seconds processing in NTP. Slightly magic.
*/
static void
tc_windup(void)
{
struct bintime bt;
struct timehands *th, *tho;
u_int64_t scale;
u_int delta, ncount, ogen;
int i;
time_t t;
/*
* Make the next timehands a copy of the current one, but do not
* overwrite the generation or next pointer. While we update
* the contents, the generation must be zero.
*/
tho = timehands;
th = tho->th_next;
ogen = th->th_generation;
th->th_generation = 0;
bcopy(tho, th, offsetof(struct timehands, th_generation));
/*
* Capture a timecounter delta on the current timecounter and if
* changing timecounters, a counter value from the new timecounter.
* Update the offset fields accordingly.
*/
delta = tc_delta(th);
if (th->th_counter != timecounter)
ncount = timecounter->tc_get_timecount(timecounter);
else
ncount = 0;
th->th_offset_count += delta;
th->th_offset_count &= th->th_counter->tc_counter_mask;
bintime_addx(&th->th_offset, th->th_scale * delta);
/*
* Hardware latching timecounters may not generate interrupts on
* PPS events, so instead we poll them. There is a finite risk that
* the hardware might capture a count which is later than the one we
* got above, and therefore possibly in the next NTP second which might
* have a different rate than the current NTP second. It doesn't
* matter in practice.
*/
if (tho->th_counter->tc_poll_pps)
tho->th_counter->tc_poll_pps(tho->th_counter);
/*
* Deal with NTP second processing. The for loop normally
* iterates at most once, but in extreme situations it might
* keep NTP sane if timeouts are not run for several seconds.
* At boot, the time step can be large when the TOD hardware
* has been read, so on really large steps, we call
* ntp_update_second only twice. We need to call it twice in
* case we missed a leap second.
*/
bt = th->th_offset;
bintime_add(&bt, &boottimebin);
i = bt.sec - tho->th_microtime.tv_sec;
if (i > LARGE_STEP)
i = 2;
for (; i > 0; i--) {
t = bt.sec;
ntp_update_second(&th->th_adjustment, &bt.sec);
if (bt.sec != t)
boottimebin.sec += bt.sec - t;
}
/* Update the UTC timestamps used by the get*() functions. */
/* XXX shouldn't do this here. Should force non-`get' versions. */
bintime2timeval(&bt, &th->th_microtime);
bintime2timespec(&bt, &th->th_nanotime);
/* Now is a good time to change timecounters. */
if (th->th_counter != timecounter) {
th->th_counter = timecounter;
th->th_offset_count = ncount;
}
/*-
* Recalculate the scaling factor. We want the number of 1/2^64
* fractions of a second per period of the hardware counter, taking
* into account the th_adjustment factor which the NTP PLL/adjtime(2)
* processing provides us with.
*
* The th_adjustment is nanoseconds per second with 32 bit binary
* fraction and we want 64 bit binary fraction of second:
*
* x = a * 2^32 / 10^9 = a * 4.294967296
*
* The range of th_adjustment is +/- 5000PPM so inside a 64bit int
* we can only multiply by about 850 without overflowing, that
* leaves no suitably precise fractions for multiply before divide.
*
* Divide before multiply with a fraction of 2199/512 results in a
* systematic undercompensation of 10PPM of th_adjustment. On a
* 5000PPM adjustment this is a 0.05PPM error. This is acceptable.
*
* We happily sacrifice the lowest of the 64 bits of our result
* to the goddess of code clarity.
*
*/
scale = (u_int64_t)1 << 63;
scale += (th->th_adjustment / 1024) * 2199;
scale /= th->th_counter->tc_frequency;
th->th_scale = scale * 2;
/*
* Now that the struct timehands is again consistent, set the new
* generation number, making sure to not make it zero.
*/
if (++ogen == 0)
ogen = 1;
th->th_generation = ogen;
/* Go live with the new struct timehands. */
time_second = th->th_microtime.tv_sec;
time_uptime = th->th_offset.sec;
timehands = th;
}
/* Report or change the active timecounter hardware. */
static int
sysctl_kern_timecounter_hardware(SYSCTL_HANDLER_ARGS)
{
char newname[32];
struct timecounter *newtc, *tc;
int error;
tc = timecounter;
strlcpy(newname, tc->tc_name, sizeof(newname));
error = sysctl_handle_string(oidp, &newname[0], sizeof(newname), req);
if (error != 0 || req->newptr == NULL ||
strcmp(newname, tc->tc_name) == 0)
return (error);
for (newtc = timecounters; newtc != NULL; newtc = newtc->tc_next) {
if (strcmp(newname, newtc->tc_name) != 0)
continue;
/* Warm up new timecounter. */
(void)newtc->tc_get_timecount(newtc);
(void)newtc->tc_get_timecount(newtc);
timecounter = newtc;
return (0);
}
return (EINVAL);
}
SYSCTL_PROC(_kern_timecounter, OID_AUTO, hardware, CTLTYPE_STRING | CTLFLAG_RW,
0, 0, sysctl_kern_timecounter_hardware, "A", "");
/* Report or change the active timecounter hardware. */
static int
sysctl_kern_timecounter_choice(SYSCTL_HANDLER_ARGS)
{
char buf[32], *spc;
struct timecounter *tc;
int error;
spc = "";
error = 0;
for (tc = timecounters; error == 0 && tc != NULL; tc = tc->tc_next) {
sprintf(buf, "%s%s(%d)",
spc, tc->tc_name, tc->tc_quality);
error = SYSCTL_OUT(req, buf, strlen(buf));
spc = " ";
}
return (error);
}
SYSCTL_PROC(_kern_timecounter, OID_AUTO, choice, CTLTYPE_STRING | CTLFLAG_RD,
0, 0, sysctl_kern_timecounter_choice, "A", "");
/*
* RFC 2783 PPS-API implementation.
*/
int
pps_ioctl(u_long cmd, caddr_t data, struct pps_state *pps)
{
pps_params_t *app;
struct pps_fetch_args *fapi;
#ifdef PPS_SYNC
struct pps_kcbind_args *kapi;
#endif
KASSERT(pps != NULL, ("NULL pps pointer in pps_ioctl"));
switch (cmd) {
case PPS_IOC_CREATE:
return (0);
case PPS_IOC_DESTROY:
return (0);
case PPS_IOC_SETPARAMS:
app = (pps_params_t *)data;
if (app->mode & ~pps->ppscap)
return (EINVAL);
pps->ppsparam = *app;
return (0);
case PPS_IOC_GETPARAMS:
app = (pps_params_t *)data;
*app = pps->ppsparam;
app->api_version = PPS_API_VERS_1;
return (0);
case PPS_IOC_GETCAP:
*(int*)data = pps->ppscap;
return (0);
case PPS_IOC_FETCH:
fapi = (struct pps_fetch_args *)data;
if (fapi->tsformat && fapi->tsformat != PPS_TSFMT_TSPEC)
return (EINVAL);
if (fapi->timeout.tv_sec || fapi->timeout.tv_nsec)
return (EOPNOTSUPP);
pps->ppsinfo.current_mode = pps->ppsparam.mode;
fapi->pps_info_buf = pps->ppsinfo;
return (0);
case PPS_IOC_KCBIND:
#ifdef PPS_SYNC
kapi = (struct pps_kcbind_args *)data;
/* XXX Only root should be able to do this */
if (kapi->tsformat && kapi->tsformat != PPS_TSFMT_TSPEC)
return (EINVAL);
if (kapi->kernel_consumer != PPS_KC_HARDPPS)
return (EINVAL);
if (kapi->edge & ~pps->ppscap)
return (EINVAL);
pps->kcmode = kapi->edge;
return (0);
#else
return (EOPNOTSUPP);
#endif
default:
return (ENOIOCTL);
}
}
void
pps_init(struct pps_state *pps)
{
pps->ppscap |= PPS_TSFMT_TSPEC;
if (pps->ppscap & PPS_CAPTUREASSERT)
pps->ppscap |= PPS_OFFSETASSERT;
if (pps->ppscap & PPS_CAPTURECLEAR)
pps->ppscap |= PPS_OFFSETCLEAR;
}
void
pps_capture(struct pps_state *pps)
{
struct timehands *th;
KASSERT(pps != NULL, ("NULL pps pointer in pps_capture"));
th = timehands;
pps->capgen = th->th_generation;
pps->capth = th;
pps->capcount = th->th_counter->tc_get_timecount(th->th_counter);
if (pps->capgen != th->th_generation)
pps->capgen = 0;
}
void
pps_event(struct pps_state *pps, int event)
{
struct bintime bt;
struct timespec ts, *tsp, *osp;
u_int tcount, *pcount;
int foff, fhard;
pps_seq_t *pseq;
KASSERT(pps != NULL, ("NULL pps pointer in pps_event"));
/* If the timecounter was wound up underneath us, bail out. */
if (pps->capgen == 0 || pps->capgen != pps->capth->th_generation)
return;
/* Things would be easier with arrays. */
if (event == PPS_CAPTUREASSERT) {
tsp = &pps->ppsinfo.assert_timestamp;
osp = &pps->ppsparam.assert_offset;
foff = pps->ppsparam.mode & PPS_OFFSETASSERT;
fhard = pps->kcmode & PPS_CAPTUREASSERT;
pcount = &pps->ppscount[0];
pseq = &pps->ppsinfo.assert_sequence;
} else {
tsp = &pps->ppsinfo.clear_timestamp;
osp = &pps->ppsparam.clear_offset;
foff = pps->ppsparam.mode & PPS_OFFSETCLEAR;
fhard = pps->kcmode & PPS_CAPTURECLEAR;
pcount = &pps->ppscount[1];
pseq = &pps->ppsinfo.clear_sequence;
}
/*
* If the timecounter changed, we cannot compare the count values, so
* we have to drop the rest of the PPS-stuff until the next event.
*/
if (pps->ppstc != pps->capth->th_counter) {
pps->ppstc = pps->capth->th_counter;
*pcount = pps->capcount;
pps->ppscount[2] = pps->capcount;
return;
}
/* Convert the count to a timespec. */
tcount = pps->capcount - pps->capth->th_offset_count;
tcount &= pps->capth->th_counter->tc_counter_mask;
bt = pps->capth->th_offset;
bintime_addx(&bt, pps->capth->th_scale * tcount);
bintime_add(&bt, &boottimebin);
bintime2timespec(&bt, &ts);
/* If the timecounter was wound up underneath us, bail out. */
if (pps->capgen != pps->capth->th_generation)
return;
*pcount = pps->capcount;
(*pseq)++;
*tsp = ts;
if (foff) {
timespecadd(tsp, osp);
if (tsp->tv_nsec < 0) {
tsp->tv_nsec += 1000000000;
tsp->tv_sec -= 1;
}
}
#ifdef PPS_SYNC
if (fhard) {
u_int64_t scale;
/*
* Feed the NTP PLL/FLL.
* The FLL wants to know how many (hardware) nanoseconds
* elapsed since the previous event.
*/
tcount = pps->capcount - pps->ppscount[2];
pps->ppscount[2] = pps->capcount;
tcount &= pps->capth->th_counter->tc_counter_mask;
scale = (u_int64_t)1 << 63;
scale /= pps->capth->th_counter->tc_frequency;
scale *= 2;
bt.sec = 0;
bt.frac = 0;
bintime_addx(&bt, scale * tcount);
bintime2timespec(&bt, &ts);
hardpps(tsp, ts.tv_nsec + 1000000000 * ts.tv_sec);
}
#endif
}
/*
* Timecounters need to be updated every so often to prevent the hardware
* counter from overflowing. Updating also recalculates the cached values
* used by the get*() family of functions, so their precision depends on
* the update frequency.
*/
static int tc_tick;
SYSCTL_INT(_kern_timecounter, OID_AUTO, tick, CTLFLAG_RD, &tc_tick, 0, "");
void
tc_ticktock(void)
{
static int count;
static time_t last_calib;
if (++count < tc_tick)
return;
count = 0;
tc_windup();
if (time_uptime != last_calib && !(time_uptime & 0xf)) {
cpu_tick_calibrate(0);
last_calib = time_uptime;
}
}
static void
inittimecounter(void *dummy)
{
u_int p;
/*
* Set the initial timeout to
* max(1, <approx. number of hardclock ticks in a millisecond>).
* People should probably not use the sysctl to set the timeout
* to smaller than its inital value, since that value is the
* smallest reasonable one. If they want better timestamps they
* should use the non-"get"* functions.
*/
if (hz > 1000)
tc_tick = (hz + 500) / 1000;
else
tc_tick = 1;
p = (tc_tick * 1000000) / hz;
printf("Timecounters tick every %d.%03u msec\n", p / 1000, p % 1000);
/* warm up new timecounter (again) and get rolling. */
(void)timecounter->tc_get_timecount(timecounter);
(void)timecounter->tc_get_timecount(timecounter);
}
SYSINIT(timecounter, SI_SUB_CLOCKS, SI_ORDER_SECOND, inittimecounter, NULL);
/* Cpu tick handling -------------------------------------------------*/
static int cpu_tick_variable;
static uint64_t cpu_tick_frequency;
static uint64_t
tc_cpu_ticks(void)
{
static uint64_t base;
static unsigned last;
unsigned u;
struct timecounter *tc;
tc = timehands->th_counter;
u = tc->tc_get_timecount(tc) & tc->tc_counter_mask;
if (u < last)
base += (uint64_t)tc->tc_counter_mask + 1;
last = u;
return (u + base);
}
/*
* This function gets called every 16 seconds on only one designated
* CPU in the system from hardclock() via tc_ticktock().
*
* Whenever the real time clock is stepped we get called with reset=1
* to make sure we handle suspend/resume and similar events correctly.
*/
static void
cpu_tick_calibrate(int reset)
{
static uint64_t c_last;
uint64_t c_this, c_delta;
static struct bintime t_last;
struct bintime t_this, t_delta;
uint32_t divi;
if (reset) {
/* The clock was stepped, abort & reset */
t_last.sec = 0;
return;
}
/* we don't calibrate fixed rate cputicks */
if (!cpu_tick_variable)
return;
getbinuptime(&t_this);
c_this = cpu_ticks();
if (t_last.sec != 0) {
c_delta = c_this - c_last;
t_delta = t_this;
bintime_sub(&t_delta, &t_last);
/*
* Validate that 16 +/- 1/256 seconds passed.
* After division by 16 this gives us a precision of
* roughly 250PPM which is sufficient
*/
if (t_delta.sec > 16 || (
t_delta.sec == 16 && t_delta.frac >= (0x01LL << 56))) {
/* too long */
if (bootverbose)
printf("t_delta %ju.%016jx too long\n",
(uintmax_t)t_delta.sec,
(uintmax_t)t_delta.frac);
} else if (t_delta.sec < 15 ||
(t_delta.sec == 15 && t_delta.frac <= (0xffLL << 56))) {
/* too short */
if (bootverbose)
printf("t_delta %ju.%016jx too short\n",
(uintmax_t)t_delta.sec,
(uintmax_t)t_delta.frac);
} else {
/* just right */
/*
* Headroom:
* 2^(64-20) / 16[s] =
* 2^(44) / 16[s] =
* 17.592.186.044.416 / 16 =
* 1.099.511.627.776 [Hz]
*/
divi = t_delta.sec << 20;
divi |= t_delta.frac >> (64 - 20);
c_delta <<= 20;
c_delta /= divi;
if (c_delta > cpu_tick_frequency) {
if (0 && bootverbose)
printf("cpu_tick increased to %ju Hz\n",
c_delta);
cpu_tick_frequency = c_delta;
}
}
}
c_last = c_this;
t_last = t_this;
}
void
set_cputicker(cpu_tick_f *func, uint64_t freq, unsigned var)
{
if (func == NULL) {
cpu_ticks = tc_cpu_ticks;
} else {
cpu_tick_frequency = freq;
cpu_tick_variable = var;
cpu_ticks = func;
}
}
uint64_t
cpu_tickrate(void)
{
if (cpu_ticks == tc_cpu_ticks)
return (tc_getfrequency());
return (cpu_tick_frequency);
}
/*
* We need to be slightly careful converting cputicks to microseconds.
* There is plenty of margin in 64 bits of microseconds (half a million
* years) and in 64 bits at 4 GHz (146 years), but if we do a multiply
* before divide conversion (to retain precision) we find that the
* margin shrinks to 1.5 hours (one millionth of 146y).
* With a three prong approach we never lose significant bits, no
* matter what the cputick rate and length of timeinterval is.
*/
uint64_t
cputick2usec(uint64_t tick)
{
if (tick > 18446744073709551LL) /* floor(2^64 / 1000) */
return (tick / (cpu_tickrate() / 1000000LL));
else if (tick > 18446744073709LL) /* floor(2^64 / 1000000) */
return ((tick * 1000LL) / (cpu_tickrate() / 1000LL));
else
return ((tick * 1000000LL) / cpu_tickrate());
}
cpu_tick_f *cpu_ticks = tc_cpu_ticks;