kern_cctr.c revision 1.10
1 /* $NetBSD: kern_cctr.c,v 1.10 2019/06/24 06:24:33 skrll Exp $ */ 2 3 /*- 4 * Copyright (c) 2006, 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * re-implementation of TSC for MP systems merging cc_microtime and 8 * TSC for timecounters by Frank Kardel 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* basic calibration ideas are (kern_microtime.c): */ 33 /****************************************************************************** 34 * * 35 * Copyright (c) David L. Mills 1993, 1994 * 36 * * 37 * Permission to use, copy, modify, and distribute this software and its * 38 * documentation for any purpose and without fee is hereby granted, provided * 39 * that the above copyright notice appears in all copies and that both the * 40 * copyright notice and this permission notice appear in supporting * 41 * documentation, and that the name University of Delaware not be used in * 42 * advertising or publicity pertaining to distribution of the software * 43 * without specific, written prior permission. The University of Delaware * 44 * makes no representations about the suitability this software for any * 45 * purpose. It is provided "as is" without express or implied warranty. * 46 * * 47 ******************************************************************************/ 48 49 /* reminiscents from older version of this file are: */ 50 /*- 51 * Copyright (c) 1998-2003 Poul-Henning Kamp 52 * All rights reserved. 53 * 54 * Redistribution and use in source and binary forms, with or without 55 * modification, are permitted provided that the following conditions 56 * are met: 57 * 1. Redistributions of source code must retain the above copyright 58 * notice, this list of conditions and the following disclaimer. 59 * 2. Redistributions in binary form must reproduce the above copyright 60 * notice, this list of conditions and the following disclaimer in the 61 * documentation and/or other materials provided with the distribution. 62 * 63 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 64 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 65 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 66 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 67 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 68 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 69 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 70 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 71 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 72 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 73 * SUCH DAMAGE. 74 */ 75 76 #include <sys/cdefs.h> 77 /* __FBSDID("$FreeBSD: src/sys/i386/i386/tsc.c,v 1.204 2003/10/21 18:28:34 silby Exp $"); */ 78 __KERNEL_RCSID(0, "$NetBSD: kern_cctr.c,v 1.10 2019/06/24 06:24:33 skrll Exp $"); 79 80 #include <sys/param.h> 81 #include <sys/systm.h> 82 #include <sys/sysctl.h> 83 #include <sys/time.h> 84 #include <sys/timetc.h> 85 #include <sys/kernel.h> 86 #include <sys/power.h> 87 #include <sys/cpu.h> 88 #include <machine/cpu_counter.h> 89 90 /* XXX make cc_timecounter.tc_frequency settable by sysctl() */ 91 92 static timecounter_pps_t cc_calibrate; 93 94 void cc_calibrate_cpu(struct cpu_info *); 95 96 static int64_t cc_cal_val; /* last calibrate time stamp */ 97 98 static struct timecounter cc_timecounter = { 99 .tc_get_timecount = cc_get_timecount, 100 .tc_poll_pps = cc_calibrate, 101 .tc_counter_mask = ~0u, 102 .tc_frequency = 0, 103 .tc_name = "unknown cycle counter", 104 /* 105 * don't pick cycle counter automatically 106 * if frequency changes might affect cycle counter 107 */ 108 .tc_quality = -100000, 109 110 .tc_priv = NULL, 111 .tc_next = NULL 112 }; 113 114 /* 115 * initialize cycle counter based timecounter 116 */ 117 struct timecounter * 118 cc_init(timecounter_get_t getcc, uint64_t freq, const char *name, int quality) 119 { 120 121 if (getcc != NULL) 122 cc_timecounter.tc_get_timecount = getcc; 123 124 cc_timecounter.tc_frequency = freq; 125 cc_timecounter.tc_name = name; 126 cc_timecounter.tc_quality = quality; 127 tc_init(&cc_timecounter); 128 129 return &cc_timecounter; 130 } 131 132 /* 133 * pick up tick count scaled to reference tick count 134 */ 135 u_int 136 cc_get_timecount(struct timecounter *tc) 137 { 138 struct cpu_info *ci; 139 int64_t rcc, cc, ncsw; 140 u_int gen; 141 142 retry: 143 ncsw = curlwp->l_ncsw; 144 __insn_barrier(); 145 ci = curcpu(); 146 if (ci->ci_cc.cc_denom == 0) { 147 /* 148 * This is our first time here on this CPU. Just 149 * start with reasonable initial values. 150 */ 151 ci->ci_cc.cc_cc = cpu_counter32(); 152 ci->ci_cc.cc_val = 0; 153 if (ci->ci_cc.cc_gen == 0) 154 ci->ci_cc.cc_gen++; 155 156 ci->ci_cc.cc_denom = cpu_frequency(ci); 157 if (ci->ci_cc.cc_denom == 0) 158 ci->ci_cc.cc_denom = cc_timecounter.tc_frequency; 159 ci->ci_cc.cc_delta = ci->ci_cc.cc_denom; 160 } 161 162 /* 163 * read counter and re-read when the re-calibration 164 * strikes inbetween 165 */ 166 do { 167 /* pick up current generation number */ 168 gen = ci->ci_cc.cc_gen; 169 170 /* determine local delta ticks */ 171 cc = cpu_counter32() - ci->ci_cc.cc_cc; 172 if (cc < 0) 173 cc += 0x100000000LL; 174 175 /* scale to primary */ 176 rcc = (cc * ci->ci_cc.cc_delta) / ci->ci_cc.cc_denom 177 + ci->ci_cc.cc_val; 178 } while (gen == 0 || gen != ci->ci_cc.cc_gen); 179 __insn_barrier(); 180 if (ncsw != curlwp->l_ncsw) { 181 /* Was preempted */ 182 goto retry; 183 } 184 185 return rcc; 186 } 187 188 /* 189 * called once per clock tick via the pps callback 190 * for the calibration of the TSC counters. 191 * it is called only for the PRIMARY cpu. all 192 * other cpus are called via a broadcast IPI 193 * calibration interval is 1 second - we call 194 * the calibration code only every hz calls 195 */ 196 static void 197 cc_calibrate(struct timecounter *tc) 198 { 199 static int calls; 200 struct cpu_info *ci; 201 202 KASSERT(kpreempt_disabled()); 203 204 /* 205 * XXX: for high interrupt frequency 206 * support: ++calls < hz / tc_tick 207 */ 208 if (++calls < hz) 209 return; 210 211 calls = 0; 212 ci = curcpu(); 213 /* pick up reference ticks */ 214 cc_cal_val = cpu_counter32(); 215 216 #if defined(MULTIPROCESSOR) 217 cc_calibrate_mp(ci); 218 #endif 219 cc_calibrate_cpu(ci); 220 } 221 222 /* 223 * This routine is called about once per second directly by the master 224 * processor and via an interprocessor interrupt for other processors. 225 * It determines the CC frequency of each processor relative to the 226 * master clock and the time this determination is made. These values 227 * are used by cc_get_timecount() to interpolate the ticks between 228 * timer interrupts. Note that we assume the kernel variables have 229 * been zeroed early in life. 230 */ 231 void 232 cc_calibrate_cpu(struct cpu_info *ci) 233 { 234 u_int gen; 235 int64_t val; 236 int64_t delta, denom; 237 int s; 238 #ifdef TIMECOUNTER_DEBUG 239 int64_t factor, old_factor; 240 #endif 241 val = cc_cal_val; 242 243 s = splhigh(); 244 /* create next generation number */ 245 gen = ci->ci_cc.cc_gen; 246 gen++; 247 if (gen == 0) 248 gen++; 249 250 /* update in progress */ 251 ci->ci_cc.cc_gen = 0; 252 253 denom = ci->ci_cc.cc_cc; 254 ci->ci_cc.cc_cc = cpu_counter32(); 255 256 if (ci->ci_cc.cc_denom == 0) { 257 /* 258 * This is our first time here on this CPU. Just 259 * start with reasonable initial values. 260 */ 261 ci->ci_cc.cc_val = val; 262 ci->ci_cc.cc_denom = cpu_frequency(ci); 263 if (ci->ci_cc.cc_denom == 0) 264 ci->ci_cc.cc_denom = cc_timecounter.tc_frequency; 265 ci->ci_cc.cc_delta = ci->ci_cc.cc_denom; 266 ci->ci_cc.cc_gen = gen; 267 splx(s); 268 return; 269 } 270 271 #ifdef TIMECOUNTER_DEBUG 272 old_factor = (ci->ci_cc.cc_delta * 1000 ) / ci->ci_cc.cc_denom; 273 #endif 274 275 /* local ticks per period */ 276 denom = ci->ci_cc.cc_cc - denom; 277 if (denom < 0) 278 denom += 0x100000000LL; 279 280 ci->ci_cc.cc_denom = denom; 281 282 /* reference ticks per period */ 283 delta = val - ci->ci_cc.cc_val; 284 if (delta < 0) 285 delta += 0x100000000LL; 286 287 ci->ci_cc.cc_val = val; 288 ci->ci_cc.cc_delta = delta; 289 290 /* publish new generation number */ 291 ci->ci_cc.cc_gen = gen; 292 splx(s); 293 294 #ifdef TIMECOUNTER_DEBUG 295 factor = (delta * 1000) / denom - old_factor; 296 if (factor < 0) 297 factor = -factor; 298 299 if (factor > old_factor / 10) 300 printf("cc_calibrate_cpu[%u]: 10%% exceeded - delta %" 301 PRId64 ", denom %" PRId64 ", factor %" PRId64 302 ", old factor %" PRId64"\n", ci->ci_index, 303 delta, denom, (delta * 1000) / denom, old_factor); 304 #endif /* TIMECOUNTER_DEBUG */ 305 } 306
Indexes created Thu Sep 25 16:09:42 GMT 2025