2 * Copyright (c) 2001 Jake Burkholder.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
30 #include <sys/param.h>
31 #include <sys/kernel.h>
32 #include <sys/systm.h>
34 #include <sys/interrupt.h>
36 #include <sys/sysctl.h>
37 #include <sys/timetc.h>
39 #include <machine/clock.h>
40 #include <machine/cpu.h>
41 #include <machine/frame.h>
42 #include <machine/intr_machdep.h>
43 #include <machine/tick.h>
44 #include <machine/ver.h>
46 #define TICK_GRACE 10000
48 SYSCTL_NODE(_machdep, OID_AUTO, tick, CTLFLAG_RD, 0, "tick statistics");
50 static int adjust_edges = 0;
51 SYSCTL_INT(_machdep_tick, OID_AUTO, adjust_edges, CTLFLAG_RD, &adjust_edges,
52 0, "total number of times tick interrupts got more than 12.5% behind");
54 static int adjust_excess = 0;
55 SYSCTL_INT(_machdep_tick, OID_AUTO, adjust_excess, CTLFLAG_RD, &adjust_excess,
56 0, "total number of ignored tick interrupts");
58 static int adjust_missed = 0;
59 SYSCTL_INT(_machdep_tick, OID_AUTO, adjust_missed, CTLFLAG_RD, &adjust_missed,
60 0, "total number of missed tick interrupts");
62 static int adjust_ticks = 0;
63 SYSCTL_INT(_machdep_tick, OID_AUTO, adjust_ticks, CTLFLAG_RD, &adjust_ticks,
64 0, "total number of tick interrupts with adjustment");
66 static void tick_hardclock(struct trapframe *);
84 tick_process(struct trapframe *tf)
87 if (PCPU_GET(cpuid) == 0)
88 hardclock(TRAPF_USERMODE(tf), TRAPF_PC(tf));
90 hardclock_cpu(TRAPF_USERMODE(tf));
92 profclock(TRAPF_USERMODE(tf), TRAPF_PC(tf));
93 statclock(TRAPF_USERMODE(tf));
97 tick_hardclock(struct trapframe *tf)
99 u_long adj, s, tick, ref;
104 * The sequence of reading the TICK register, calculating the value
105 * of the next tick and writing it to the TICK_CMPR register must not
106 * be interrupted, not even by an IPI, otherwise a value that is in
107 * the past could be written in the worst case, causing hardclock to
110 adj = PCPU_GET(tickadj);
113 wrtickcmpr(tick + tick_increment - adj, 0);
115 ref = PCPU_GET(tickref);
118 while (delta >= tick_increment) {
120 delta -= tick_increment;
121 ref += tick_increment;
127 adjust_missed += count - 1;
128 if (delta > (tick_increment >> 3)) {
131 adj = tick_increment >> 4;
138 PCPU_SET(tickref, ref);
139 PCPU_SET(tickadj, adj);
143 tick_init(u_long clock)
147 tick_MHz = clock / 1000000;
148 tick_increment = clock / hz;
151 * UltraSparc II[e,i] based systems come up with the tick interrupt
152 * enabled and a handler that resets the tick counter, causing DELAY()
153 * to not work properly when used early in boot.
154 * UltraSPARC III based systems come up with the system tick interrupt
155 * enabled, causing an interrupt storm on startup since they are not
160 set_cputicker(tick_cputicks, tick_freq, 0);
169 * Avoid stopping of hardclock in terms of a lost tick interrupt
170 * by ensuring that the tick period is at least TICK_GRACE ticks.
171 * This check would be better placed in tick_init(), however we
172 * have to call tick_init() before cninit() in order to provide
173 * the low-level console drivers with a working DELAY() which in
174 * turn means we cannot use panic() in tick_init().
176 if (tick_increment < TICK_GRACE)
177 panic("%s: HZ too high, decrease to at least %ld", __func__,
178 tick_freq / TICK_GRACE);
180 if (PCPU_GET(cpuid) == 0)
181 intr_setup(PIL_TICK, tick_hardclock, -1, NULL, NULL);
184 * Try to make the tick interrupts as synchronously as possible on
185 * all CPUs to avoid inaccuracies for migrating processes. Leave out
186 * one tick to make sure that it is not missed.
188 PCPU_SET(tickadj, 0);
191 base = roundup(base, tick_increment);
192 PCPU_SET(tickref, base);
193 wrtickcmpr(base + tick_increment, 0);
201 if (cpu_impl >= CPU_IMPL_ULTRASPARCIII)
202 wr(asr25, 1L << 63, 0);
203 wrtickcmpr(1L << 63, 0);