Add a generation number to timecounters and spin if it changes under
our feet when we look inside timecounter structures. Make the "sync_other" code more robust by never overwriting the tc_next field. Add counters for the bin[up]time functions. Call tc_windup() in tc_init() and switch_timecounter() to make sure we all the fields set right.
This commit is contained in:
Poul-Henning Kamp
parent
e9be968e95
commit
5b7d8efa8d
@ -42,6 +42,8 @@ SYSCTL_STRUCT(_kern, KERN_BOOTTIME, boottime, CTLFLAG_RD,
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SYSCTL_NODE(_kern, OID_AUTO, timecounter, CTLFLAG_RW, 0, "");
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static unsigned nbintime;
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static unsigned nbinuptime;
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static unsigned nmicrotime;
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static unsigned nnanotime;
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static unsigned ngetmicrotime;
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@ -50,6 +52,8 @@ static unsigned nmicrouptime;
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static unsigned nnanouptime;
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static unsigned ngetmicrouptime;
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static unsigned ngetnanouptime;
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SYSCTL_INT(_kern_timecounter, OID_AUTO, nbintime, CTLFLAG_RD, &nbintime, 0, "");
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SYSCTL_INT(_kern_timecounter, OID_AUTO, nbinuptime, CTLFLAG_RD, &nbinuptime, 0, "");
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SYSCTL_INT(_kern_timecounter, OID_AUTO, nmicrotime, CTLFLAG_RD, &nmicrotime, 0, "");
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SYSCTL_INT(_kern_timecounter, OID_AUTO, nnanotime, CTLFLAG_RD, &nnanotime, 0, "");
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SYSCTL_INT(_kern_timecounter, OID_AUTO, nmicrouptime, CTLFLAG_RD, &nmicrouptime, 0, "");
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@ -70,6 +74,8 @@ dummy_get_timecount(struct timecounter *tc)
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{
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static unsigned now;
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if (tc->tc_generation == 0)
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tc->tc_generation++;
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return (++now);
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}
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@ -106,16 +112,22 @@ void
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binuptime(struct bintime *bt)
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{
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struct timecounter *tc;
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unsigned gen;
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tc = timecounter;
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*bt = tc->tc_offset;
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bintime_addx(bt, tc->tc_scale * tco_delta(tc));
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nbinuptime++;
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do {
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tc = timecounter;
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gen = tc->tc_generation;
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*bt = tc->tc_offset;
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bintime_addx(bt, tc->tc_scale * tco_delta(tc));
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} while (gen == 0 || gen != tc->tc_generation);
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}
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void
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bintime(struct bintime *bt)
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{
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nbintime++;
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binuptime(bt);
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bintime_add(bt, &boottimebin);
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}
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@ -124,20 +136,28 @@ void
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getmicrotime(struct timeval *tvp)
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{
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struct timecounter *tc;
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unsigned gen;
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ngetmicrotime++;
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tc = timecounter;
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*tvp = tc->tc_microtime;
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do {
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tc = timecounter;
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gen = tc->tc_generation;
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*tvp = tc->tc_microtime;
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} while (gen == 0 || gen != tc->tc_generation);
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}
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void
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getnanotime(struct timespec *tsp)
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{
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struct timecounter *tc;
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unsigned gen;
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ngetnanotime++;
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tc = timecounter;
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*tsp = tc->tc_nanotime;
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do {
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tc = timecounter;
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gen = tc->tc_generation;
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*tsp = tc->tc_nanotime;
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} while (gen == 0 || gen != tc->tc_generation);
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}
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void
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@ -164,20 +184,28 @@ void
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getmicrouptime(struct timeval *tvp)
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{
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struct timecounter *tc;
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unsigned gen;
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ngetmicrouptime++;
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tc = timecounter;
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bintime2timeval(&tc->tc_offset, tvp);
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do {
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tc = timecounter;
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gen = tc->tc_generation;
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bintime2timeval(&tc->tc_offset, tvp);
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} while (gen == 0 || gen != tc->tc_generation);
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}
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void
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getnanouptime(struct timespec *tsp)
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{
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struct timecounter *tc;
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unsigned gen;
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ngetnanouptime++;
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tc = timecounter;
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bintime2timespec(&tc->tc_offset, tsp);
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do {
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tc = timecounter;
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gen = tc->tc_generation;
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bintime2timespec(&tc->tc_offset, tsp);
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} while (gen == 0 || gen != tc->tc_generation);
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}
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void
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@ -240,19 +268,19 @@ tc_init(struct timecounter *tc)
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tc->tc_avail = timecounter->tc_tweak->tc_avail;
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timecounter->tc_tweak->tc_avail = tc;
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}
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MALLOC(t1, struct timecounter *, sizeof *t1, M_TIMECOUNTER, M_WAITOK);
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tc->tc_other = t1;
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MALLOC(t1, struct timecounter *, sizeof *t1, M_TIMECOUNTER, M_WAITOK | M_ZERO);
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tc->tc_next = t1;
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*t1 = *tc;
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t2 = t1;
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t3 = NULL;
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for (i = 1; i < NTIMECOUNTER; i++) {
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MALLOC(t3, struct timecounter *, sizeof *t3,
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M_TIMECOUNTER, M_WAITOK);
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M_TIMECOUNTER, M_WAITOK | M_ZERO);
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*t3 = *tc;
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t3->tc_other = t2;
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t3->tc_next = t2;
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t2 = t3;
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}
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t1->tc_other = t3;
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t1->tc_next = t3;
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tc = t1;
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printf("Timecounter \"%s\" frequency %lu Hz\n",
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@ -262,6 +290,7 @@ tc_init(struct timecounter *tc)
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tc->tc_offset_count = tc->tc_get_timecount(tc);
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binuptime(&tc->tc_offset);
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timecounter = tc;
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tc_windup();
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}
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void
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@ -293,42 +322,34 @@ switch_timecounter(struct timecounter *newtc)
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splx(s);
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return;
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}
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newtc = newtc->tc_tweak->tc_other;
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newtc = newtc->tc_tweak->tc_next;
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binuptime(&newtc->tc_offset);
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newtc->tc_offset_count = newtc->tc_get_timecount(newtc);
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tco_setscales(newtc);
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newtc->tc_generation = 0;
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timecounter = newtc;
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tc_windup();
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splx(s);
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}
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static struct timecounter *
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sync_other_counter(void)
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{
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struct timecounter *tc, *tcn, *tco;
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unsigned delta;
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tco = timecounter;
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tc = tco->tc_other;
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tcn = tc->tc_other;
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*tc = *tco;
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tc->tc_other = tcn;
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delta = tco_delta(tc);
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tc->tc_offset_count += delta;
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tc->tc_offset_count &= tc->tc_counter_mask;
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bintime_addx(&tc->tc_offset, tc->tc_scale * delta);
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return (tc);
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}
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void
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tc_windup(void)
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{
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struct timecounter *tc, *tco;
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struct bintime bt;
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struct timeval tvt;
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unsigned ogen, delta;
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int i;
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tco = timecounter;
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tc = sync_other_counter();
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tc = tco->tc_next;
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ogen = tc->tc_generation;
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tc->tc_generation = 0;
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bcopy(tco, tc, __offsetof(struct timecounter, tc_generation));
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delta = tco_delta(tc);
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tc->tc_offset_count += delta;
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tc->tc_offset_count &= tc->tc_counter_mask;
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bintime_addx(&tc->tc_offset, tc->tc_scale * delta);
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/*
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* We may be inducing a tiny error here, the tc_poll_pps() may
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* process a latched count which happens after the tco_delta()
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@ -363,6 +384,10 @@ tc_windup(void)
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bintime_add(&bt, &boottimebin);
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bintime2timeval(&bt, &tc->tc_microtime);
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bintime2timespec(&bt, &tc->tc_nanotime);
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ogen++;
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if (ogen == 0)
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ogen++;
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tc->tc_generation = ogen;
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time_second = tc->tc_microtime.tv_sec;
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timecounter = tc;
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}
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@ -84,8 +84,10 @@ struct timecounter {
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struct timeval tc_microtime;
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struct timespec tc_nanotime;
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struct timecounter *tc_avail;
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struct timecounter *tc_other;
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struct timecounter *tc_tweak;
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/* Fields not to be copied in tc_windup start with tc_generation */
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volatile unsigned tc_generation;
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struct timecounter *tc_next;
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};
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#ifdef _KERNEL
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