kern_cctr.c revision 1.6
1 /* $NetBSD: kern_cctr.c,v 1.6 2008/04/27 22:43:08 ad 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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 /* basic calibration ideas are (kern_microtime.c): */ 40 /****************************************************************************** 41 * * 42 * Copyright (c) David L. Mills 1993, 1994 * 43 * * 44 * Permission to use, copy, modify, and distribute this software and its * 45 * documentation for any purpose and without fee is hereby granted, provided * 46 * that the above copyright notice appears in all copies and that both the * 47 * copyright notice and this permission notice appear in supporting * 48 * documentation, and that the name University of Delaware not be used in * 49 * advertising or publicity pertaining to distribution of the software * 50 * without specific, written prior permission. The University of Delaware * 51 * makes no representations about the suitability this software for any * 52 * purpose. It is provided "as is" without express or implied warranty. * 53 * * 54 ******************************************************************************/ 55 56 /* reminiscents from older version of this file are: */ 57 /*- 58 * Copyright (c) 1998-2003 Poul-Henning Kamp 59 * All rights reserved. 60 * 61 * Redistribution and use in source and binary forms, with or without 62 * modification, are permitted provided that the following conditions 63 * are met: 64 * 1. Redistributions of source code must retain the above copyright 65 * notice, this list of conditions and the following disclaimer. 66 * 2. Redistributions in binary form must reproduce the above copyright 67 * notice, this list of conditions and the following disclaimer in the 68 * documentation and/or other materials provided with the distribution. 69 * 70 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 71 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 72 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 73 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 74 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 75 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 76 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 77 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 78 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 79 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 80 * SUCH DAMAGE. 81 */ 82 83 #include <sys/cdefs.h> 84 /* __FBSDID("$FreeBSD: src/sys/i386/i386/tsc.c,v 1.204 2003/10/21 18:28:34 silby Exp $"); */ 85 __KERNEL_RCSID(0, "$NetBSD: kern_cctr.c,v 1.6 2008/04/27 22:43:08 ad Exp $"); 86 87 #include "opt_multiprocessor.h" 88 89 #include <sys/param.h> 90 #include <sys/systm.h> 91 #include <sys/sysctl.h> 92 #include <sys/time.h> 93 #include <sys/timetc.h> 94 #include <sys/kernel.h> 95 #include <sys/power.h> 96 #include <sys/cpu.h> 97 #include <machine/cpu_counter.h> 98 99 /* XXX make cc_timecounter.tc_frequency settable by sysctl() */ 100 101 static timecounter_pps_t cc_calibrate; 102 103 void cc_calibrate_cpu(struct cpu_info *); 104 105 static int64_t cc_cal_val; /* last calibrate time stamp */ 106 107 static struct timecounter cc_timecounter = { 108 .tc_get_timecount = cc_get_timecount, 109 .tc_poll_pps = cc_calibrate, 110 .tc_counter_mask = ~0u, 111 .tc_frequency = 0, 112 .tc_name = "unkown cycle counter", 113 /* 114 * don't pick cycle counter automatically 115 * if frequency changes might affect cycle counter 116 */ 117 .tc_quality = -100000, 118 119 .tc_priv = NULL, 120 .tc_next = NULL 121 }; 122 123 /* 124 * initialize cycle counter based timecounter 125 */ 126 struct timecounter * 127 cc_init(timecounter_get_t getcc, uint64_t freq, const char *name, int quality) 128 { 129 130 if (getcc != NULL) 131 cc_timecounter.tc_get_timecount = getcc; 132 133 cc_timecounter.tc_frequency = freq; 134 cc_timecounter.tc_name = name; 135 cc_timecounter.tc_quality = quality; 136 tc_init(&cc_timecounter); 137 138 return &cc_timecounter; 139 } 140 141 /* 142 * pick up tick count scaled to reference tick count 143 */ 144 u_int 145 cc_get_timecount(struct timecounter *tc) 146 { 147 struct cpu_info *ci; 148 int64_t rcc, cc, ncsw; 149 u_int gen; 150 151 retry: 152 ncsw = curlwp->l_ncsw; 153 __insn_barrier(); 154 ci = curcpu(); 155 if (ci->ci_cc.cc_denom == 0) { 156 /* 157 * This is our first time here on this CPU. Just 158 * start with reasonable initial values. 159 */ 160 ci->ci_cc.cc_cc = cpu_counter32(); 161 ci->ci_cc.cc_val = 0; 162 if (ci->ci_cc.cc_gen == 0) 163 ci->ci_cc.cc_gen++; 164 165 ci->ci_cc.cc_denom = cpu_frequency(ci); 166 if (ci->ci_cc.cc_denom == 0) 167 ci->ci_cc.cc_denom = cc_timecounter.tc_frequency; 168 ci->ci_cc.cc_delta = ci->ci_cc.cc_denom; 169 } 170 171 /* 172 * read counter and re-read when the re-calibration 173 * strikes inbetween 174 */ 175 do { 176 /* pick up current generation number */ 177 gen = ci->ci_cc.cc_gen; 178 179 /* determine local delta ticks */ 180 cc = cpu_counter32() - ci->ci_cc.cc_cc; 181 if (cc < 0) 182 cc += 0x100000000LL; 183 184 /* scale to primary */ 185 rcc = (cc * ci->ci_cc.cc_delta) / ci->ci_cc.cc_denom 186 + ci->ci_cc.cc_val; 187 } while (gen == 0 || gen != ci->ci_cc.cc_gen); 188 __insn_barrier(); 189 if (ncsw != curlwp->l_ncsw) { 190 /* Was preempted */ 191 goto retry; 192 } 193 194 return rcc; 195 } 196 197 /* 198 * called once per clock tick via the pps callback 199 * for the calibration of the TSC counters. 200 * it is called only for the PRIMARY cpu. all 201 * other cpus are called via a broadcast IPI 202 * calibration interval is 1 second - we call 203 * the calibration code only every hz calls 204 */ 205 static void 206 cc_calibrate(struct timecounter *tc) 207 { 208 static int calls; 209 struct cpu_info *ci; 210 211 KASSERT(kpreempt_disabled()); 212 213 /* 214 * XXX: for high interrupt frequency 215 * support: ++calls < hz / tc_tick 216 */ 217 if (++calls < hz) 218 return; 219 220 calls = 0; 221 ci = curcpu(); 222 /* pick up reference ticks */ 223 cc_cal_val = cpu_counter32(); 224 225 #if defined(MULTIPROCESSOR) 226 cc_calibrate_mp(ci); 227 #endif 228 cc_calibrate_cpu(ci); 229 } 230 231 /* 232 * This routine is called about once per second directly by the master 233 * processor and via an interprocessor interrupt for other processors. 234 * It determines the CC frequency of each processor relative to the 235 * master clock and the time this determination is made. These values 236 * are used by cc_get_timecount() to interpolate the ticks between 237 * timer interrupts. Note that we assume the kernel variables have 238 * been zeroed early in life. 239 */ 240 void 241 cc_calibrate_cpu(struct cpu_info *ci) 242 { 243 u_int gen; 244 int64_t val; 245 int64_t delta, denom; 246 int s; 247 #ifdef TIMECOUNTER_DEBUG 248 int64_t factor, old_factor; 249 #endif 250 val = cc_cal_val; 251 252 s = splhigh(); 253 /* create next generation number */ 254 gen = ci->ci_cc.cc_gen; 255 gen++; 256 if (gen == 0) 257 gen++; 258 259 /* update in progress */ 260 ci->ci_cc.cc_gen = 0; 261 262 denom = ci->ci_cc.cc_cc; 263 ci->ci_cc.cc_cc = cpu_counter32(); 264 265 if (ci->ci_cc.cc_denom == 0) { 266 /* 267 * This is our first time here on this CPU. Just 268 * start with reasonable initial values. 269 */ 270 ci->ci_cc.cc_val = val; 271 ci->ci_cc.cc_denom = cpu_frequency(ci); 272 if (ci->ci_cc.cc_denom == 0) 273 ci->ci_cc.cc_denom = cc_timecounter.tc_frequency;; 274 ci->ci_cc.cc_delta = ci->ci_cc.cc_denom; 275 ci->ci_cc.cc_gen = gen; 276 splx(s); 277 return; 278 } 279 280 #ifdef TIMECOUNTER_DEBUG 281 old_factor = (ci->ci_cc.cc_delta * 1000 ) / ci->ci_cc.cc_denom; 282 #endif 283 284 /* local ticks per period */ 285 denom = ci->ci_cc.cc_cc - denom; 286 if (denom < 0) 287 denom += 0x100000000LL; 288 289 ci->ci_cc.cc_denom = denom; 290 291 /* reference ticks per period */ 292 delta = val - ci->ci_cc.cc_val; 293 if (delta < 0) 294 delta += 0x100000000LL; 295 296 ci->ci_cc.cc_val = val; 297 ci->ci_cc.cc_delta = delta; 298 299 /* publish new generation number */ 300 ci->ci_cc.cc_gen = gen; 301 splx(s); 302 303 #ifdef TIMECOUNTER_DEBUG 304 factor = (delta * 1000) / denom - old_factor; 305 if (factor < 0) 306 factor = -factor; 307 308 if (factor > old_factor / 10) 309 printf("cc_calibrate_cpu[%u]: 10%% exceeded - delta %" 310 PRId64 ", denom %" PRId64 ", factor %" PRId64 311 ", old factor %" PRId64"\n", ci->ci_index, 312 delta, denom, (delta * 1000) / denom, old_factor); 313 #endif /* TIMECOUNTER_DEBUG */ 314 } 315
Indexes created Thu Sep 25 08:09:54 GMT 2025