| 1 | /** $Id: VBoxServiceTimeSync.cpp 6029 2007-12-09 21:51:13Z vboxsync $ */
|
|---|
| 2 | /** @file
|
|---|
| 3 | * VBoxService - Guest Additions TimeSync Service.
|
|---|
| 4 | */
|
|---|
| 5 |
|
|---|
| 6 | /*
|
|---|
| 7 | * Copyright (C) 2007 innotek GmbH
|
|---|
| 8 | *
|
|---|
| 9 | * This file is part of VirtualBox Open Source Edition (OSE), as
|
|---|
| 10 | * available from http://www.virtualbox.org. This file is free software;
|
|---|
| 11 | * you can redistribute it and/or modify it under the terms of the GNU
|
|---|
| 12 | * General Public License (GPL) as published by the Free Software
|
|---|
| 13 | * Foundation, in version 2 as it comes in the "COPYING" file of the
|
|---|
| 14 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
|
|---|
| 15 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
|
|---|
| 16 | */
|
|---|
| 17 |
|
|---|
| 18 |
|
|---|
| 19 | /** @page pg_vboxservice_timesync The Time Sync Service
|
|---|
| 20 | *
|
|---|
| 21 | * The time sync service plays along with the Time Manager (TM) in the VMM
|
|---|
| 22 | * to keep the guest time accurate using the host machine as reference.
|
|---|
| 23 | * TM will try its best to make sure all timer ticks gets delivered so that
|
|---|
| 24 | * there isn't normally any need to adjust the guest time.
|
|---|
| 25 | *
|
|---|
| 26 | * There are three normal (= acceptable) cases:
|
|---|
| 27 | * -# When the service starts up. This is because ticks and such might
|
|---|
| 28 | * be lost during VM and OS startup. (Need to figure out exactly why!)
|
|---|
| 29 | * -# When the TM is unable to deliver all the ticks and swallows a
|
|---|
| 30 | * backlog of ticks. The threshold for this is configurable with
|
|---|
| 31 | * a default of 60 seconds.
|
|---|
| 32 | * -# The time is adjusted on the host. This can be caused manually by
|
|---|
| 33 | * the user or by some time sync daemon (NTP, LAN server, etc.).
|
|---|
| 34 | *
|
|---|
| 35 | * There are a number of very odd case where adjusting is needed. Here
|
|---|
| 36 | * are some of them:
|
|---|
| 37 | * -# Timer device emulation inaccurancies (like rounding).
|
|---|
| 38 | * -# Inaccurancies in time source VirtualBox uses.
|
|---|
| 39 | * -# The Guest and/or Host OS doesn't perform proper time keeping. This
|
|---|
| 40 | * come about as a result of OS and/or hardware issues.
|
|---|
| 41 | *
|
|---|
| 42 | * The TM is our source for the host time and will make adjustments for
|
|---|
| 43 | * current timer delivery lag. The simplistic approach taken by TM is to
|
|---|
| 44 | * adjust the host time by the current guest timer delivery lag, meaning that
|
|---|
| 45 | * if the guest is behind 1 second with PIT/RTC/++ ticks this should be reflected
|
|---|
| 46 | * in the guest wall time as well.
|
|---|
| 47 | *
|
|---|
| 48 | * Now, there is any amount of trouble we can cause by changing the time.
|
|---|
| 49 | * Most applications probably uses the wall time when they need to measure
|
|---|
| 50 | * things. A walltime that is being juggled about every so often, even if just
|
|---|
| 51 | * a little bit, could occationally upset these measurements by for instance
|
|---|
| 52 | * yielding negative results.
|
|---|
| 53 | *
|
|---|
| 54 | * This bottom line here is that the time sync service isn't really supposed
|
|---|
| 55 | * to do anything and will try avoid having to do anything when possible.
|
|---|
| 56 | *
|
|---|
| 57 | * The implementation uses the latency it takes to query host time as the
|
|---|
| 58 | * absolute maximum precision to avoid messing up under timer tick catchup
|
|---|
| 59 | * and/or heavy host/guest load. (Rational is that a *lot* of stuff may happen
|
|---|
| 60 | * on our way back from ring-3 and TM/VMMDev since we're taking the route
|
|---|
| 61 | * thru the inner EM loop with it's force action processing.)
|
|---|
| 62 | *
|
|---|
| 63 | * But this latency has to be measured from our perspective, which means it
|
|---|
| 64 | * could just as easily come out as 0. (OS/2 and Windows guest only updates
|
|---|
| 65 | * the current time when the timer ticks for instance.) The good thing is
|
|---|
| 66 | * that this isn't really a problem since we won't ever do anything unless
|
|---|
| 67 | * the drift is noticable.
|
|---|
| 68 | *
|
|---|
| 69 | * It now boils down to these three (configuration) factors:
|
|---|
| 70 | * -# g_TimesyncMinAdjust - The minimum drift we will ever bother with.
|
|---|
| 71 | * -# g_TimesyncLatencyFactor - The factor we multiply the latency by to
|
|---|
| 72 | * calculate the dynamic minimum adjust factor.
|
|---|
| 73 | * -# g_TimesyncMaxLatency - When to start discarding the data as utterly
|
|---|
| 74 | * useless and take a rest (someone is too busy to give us good data).
|
|---|
| 75 | */
|
|---|
| 76 |
|
|---|
| 77 |
|
|---|
| 78 |
|
|---|
| 79 | /*******************************************************************************
|
|---|
| 80 | * Header Files *
|
|---|
| 81 | *******************************************************************************/
|
|---|
| 82 | #ifdef RT_OS_WINDOWS
|
|---|
| 83 | #else
|
|---|
| 84 | # include <unistd.h>
|
|---|
| 85 | # include <errno.h>
|
|---|
| 86 | # include <time.h>
|
|---|
| 87 | # include <sys/time.h>
|
|---|
| 88 | #endif
|
|---|
| 89 |
|
|---|
| 90 | #include <iprt/thread.h>
|
|---|
| 91 | #include <iprt/string.h>
|
|---|
| 92 | #include <iprt/semaphore.h>
|
|---|
| 93 | #include <iprt/time.h>
|
|---|
| 94 | #include <iprt/assert.h>
|
|---|
| 95 | #include <VBox/VBoxGuest.h>
|
|---|
| 96 | #include "VBoxServiceInternal.h"
|
|---|
| 97 |
|
|---|
| 98 |
|
|---|
| 99 | /*******************************************************************************
|
|---|
| 100 | * Global Variables *
|
|---|
| 101 | *******************************************************************************/
|
|---|
| 102 | /** The timesync interval (millseconds). */
|
|---|
| 103 | uint32_t g_TimeSyncInterval = 0;
|
|---|
| 104 | /**
|
|---|
| 105 | * @see pg_vboxservice_timesync
|
|---|
| 106 | *
|
|---|
| 107 | * @remark OS/2: There is either a 1 second resolution on the DosSetDateTime
|
|---|
| 108 | * API or a but in the settimeofday implementation. Thus, don't
|
|---|
| 109 | * bother unless there is at least a 1 second drift.
|
|---|
| 110 | */
|
|---|
| 111 | #ifdef RT_OS_OS2
|
|---|
| 112 | static uint32_t g_TimeSyncMinAdjust = 1000;
|
|---|
| 113 | #else
|
|---|
| 114 | static uint32_t g_TimeSyncMinAdjust = 100;
|
|---|
| 115 | #endif
|
|---|
| 116 | /** @see pg_vboxservice_timesync */
|
|---|
| 117 | static uint32_t g_TimeSyncLatencyFactor = 8;
|
|---|
| 118 | /** @see pg_vboxservice_timesync */
|
|---|
| 119 | static uint32_t g_TimeSyncMaxLatency = 250;
|
|---|
| 120 |
|
|---|
| 121 | /** The semaphore we're blocking on. */
|
|---|
| 122 | static RTSEMEVENTMULTI g_TimeSyncEvent = NIL_RTSEMEVENTMULTI;
|
|---|
| 123 |
|
|---|
| 124 |
|
|---|
| 125 | /** @copydoc VBOXSERVICE::pfnPreInit */
|
|---|
| 126 | static DECLCALLBACK(int) VBoxServiceTimeSyncPreInit(void)
|
|---|
| 127 | {
|
|---|
| 128 | return VINF_SUCCESS;
|
|---|
| 129 | }
|
|---|
| 130 |
|
|---|
| 131 |
|
|---|
| 132 | /** @copydoc VBOXSERVICE::pfnOption */
|
|---|
| 133 | static DECLCALLBACK(int) VBoxServiceTimeSyncOption(const char **ppszShort, int argc, char **argv, int *pi)
|
|---|
| 134 | {
|
|---|
| 135 | int rc = -1;
|
|---|
| 136 | if (ppszShort)
|
|---|
| 137 | /* no short options */;
|
|---|
| 138 | else if (!strcmp(argv[*pi], "--timesync-interval"))
|
|---|
| 139 | rc = VBoxServiceArgUInt32(argc, argv, "", pi,
|
|---|
| 140 | &g_TimeSyncInterval, 1, UINT32_MAX - 1);
|
|---|
| 141 | else if (!strcmp(argv[*pi], "--timesync-min-adjust"))
|
|---|
| 142 | rc = VBoxServiceArgUInt32(argc, argv, "", pi,
|
|---|
| 143 | &g_TimeSyncMinAdjust, 0, 3600000);
|
|---|
| 144 | else if (!strcmp(argv[*pi], "--timesync-latency-factor"))
|
|---|
| 145 | rc = VBoxServiceArgUInt32(argc, argv, "", pi,
|
|---|
| 146 | &g_TimeSyncLatencyFactor, 1, 1024);
|
|---|
| 147 | else if (!strcmp(argv[*pi], "--timesync-max-latency"))
|
|---|
| 148 | rc = VBoxServiceArgUInt32(argc, argv, "", pi,
|
|---|
| 149 | &g_TimeSyncMaxLatency, 1, 3600000);
|
|---|
| 150 | return rc;
|
|---|
| 151 | }
|
|---|
| 152 |
|
|---|
| 153 |
|
|---|
| 154 | /** @copydoc VBOXSERVICE::pfnInit */
|
|---|
| 155 | static DECLCALLBACK(int) VBoxServiceTimeSyncInit(void)
|
|---|
| 156 | {
|
|---|
| 157 | /*
|
|---|
| 158 | * If not specified, find the right interval default.
|
|---|
| 159 | * Then create the event sem to block on.
|
|---|
| 160 | */
|
|---|
| 161 | if (!g_TimeSyncInterval)
|
|---|
| 162 | g_TimeSyncInterval = g_DefaultInterval * 1000;
|
|---|
| 163 | if (!g_TimeSyncInterval)
|
|---|
| 164 | g_TimeSyncInterval = 10 * 1000;
|
|---|
| 165 |
|
|---|
| 166 | int rc = RTSemEventMultiCreate(&g_TimeSyncEvent);
|
|---|
| 167 | AssertRC(rc);
|
|---|
| 168 | return rc;
|
|---|
| 169 | }
|
|---|
| 170 |
|
|---|
| 171 |
|
|---|
| 172 | /** @copydoc VBOXSERVICE::pfnWorker */
|
|---|
| 173 | DECLCALLBACK(int) VBoxServiceTimeSyncWorker(bool volatile *pfShutdown)
|
|---|
| 174 | {
|
|---|
| 175 | RTTIME Time;
|
|---|
| 176 | char sz[64];
|
|---|
| 177 | int rc;
|
|---|
| 178 |
|
|---|
| 179 | unsigned cErrors = 0;
|
|---|
| 180 | for (;;)
|
|---|
| 181 | {
|
|---|
| 182 | /*
|
|---|
| 183 | * Try get a reliable time reading.
|
|---|
| 184 | */
|
|---|
| 185 | int cTries = 3;
|
|---|
| 186 | do
|
|---|
| 187 | {
|
|---|
| 188 | /* query it. */
|
|---|
| 189 | RTTIMESPEC GuestNow0, GuestNow, HostNow;
|
|---|
| 190 | RTTimeNow(&GuestNow0);
|
|---|
| 191 | int rc2 = VbglR3GetHostTime(&HostNow);
|
|---|
| 192 | if (RT_FAILURE(rc2))
|
|---|
| 193 | {
|
|---|
| 194 | if (cErrors++ < 10)
|
|---|
| 195 | VBoxServiceError("VbglR3GetHostTime failed; rc2=%Rrc\n", rc2);
|
|---|
| 196 | break;
|
|---|
| 197 | }
|
|---|
| 198 | RTTimeNow(&GuestNow);
|
|---|
| 199 |
|
|---|
| 200 | /* calc latency and check if it's ok. */
|
|---|
| 201 | RTTIMESPEC GuestElapsed = GuestNow;
|
|---|
| 202 | RTTimeSpecSub(&GuestElapsed, &GuestNow0);
|
|---|
| 203 | if ((uint32_t)RTTimeSpecGetMilli(&GuestElapsed) < g_TimeSyncMaxLatency)
|
|---|
| 204 | {
|
|---|
| 205 | /*
|
|---|
| 206 | * Calculate the adjustment threshold and the current drift.
|
|---|
| 207 | */
|
|---|
| 208 | uint32_t MinAdjust = RTTimeSpecGetMilli(&GuestElapsed) * g_TimeSyncLatencyFactor;
|
|---|
| 209 | if (MinAdjust < g_TimeSyncMinAdjust)
|
|---|
| 210 | MinAdjust = g_TimeSyncMinAdjust;
|
|---|
| 211 |
|
|---|
| 212 | RTTIMESPEC Drift = HostNow;
|
|---|
| 213 | RTTimeSpecSub(&Drift, &GuestNow);
|
|---|
| 214 | if (RTTimeSpecGetMilli(&Drift) < 0)
|
|---|
| 215 | MinAdjust += g_TimeSyncMinAdjust; /* extra buffer against moving time backwards. */
|
|---|
| 216 |
|
|---|
| 217 | RTTIMESPEC AbsDrift = Drift;
|
|---|
| 218 | RTTimeSpecAbsolute(&AbsDrift);
|
|---|
| 219 | if (g_cVerbosity >= 3)
|
|---|
| 220 | {
|
|---|
| 221 | VBoxServiceVerbose(3, "Host: %s (MinAdjust: %RU32 ms)\n",
|
|---|
| 222 | RTTimeToString(RTTimeExplode(&Time, &HostNow), sz, sizeof(sz)), MinAdjust);
|
|---|
| 223 | VBoxServiceVerbose(3, "Guest: - %s => %RDtimespec drift\n",
|
|---|
| 224 | RTTimeToString(RTTimeExplode(&Time, &GuestNow), sz, sizeof(sz)),
|
|---|
| 225 | &Drift);
|
|---|
| 226 | }
|
|---|
| 227 | if (RTTimeSpecGetMilli(&AbsDrift) > MinAdjust)
|
|---|
| 228 | {
|
|---|
| 229 | /*
|
|---|
| 230 | * The drift is to big, we have to make adjustments. :-/
|
|---|
| 231 | * If we've got adjtime around, try that first - most
|
|---|
| 232 | * *NIX systems have it. Fall back on settimeofday.
|
|---|
| 233 | */
|
|---|
| 234 | #ifdef RT_OS_WINDOWS
|
|---|
| 235 | /* just make sure it compiles for now, but later:
|
|---|
| 236 | SetSystemTimeAdjustment and fall back on SetSystemTime.
|
|---|
| 237 | */
|
|---|
| 238 | AssertFatalFailed();
|
|---|
| 239 | #else
|
|---|
| 240 | struct timeval tv;
|
|---|
| 241 | # if !defined(RT_OS_OS2) /* PORTME */
|
|---|
| 242 | RTTimeSpecGetTimeval(Drift, &tv);
|
|---|
| 243 | if (adjtime(&tv, NULL) == 0)
|
|---|
| 244 | {
|
|---|
| 245 | if (g_cVerbosity >= 1)
|
|---|
| 246 | VBoxServiceVerbose(1, "adjtime by %RDtimespec\n", &Drift);
|
|---|
| 247 | cErrors = 0;
|
|---|
| 248 | }
|
|---|
| 249 | else
|
|---|
| 250 | # endif
|
|---|
| 251 | {
|
|---|
| 252 | errno = 0;
|
|---|
| 253 | if (!gettimeofday(&tv, NULL))
|
|---|
| 254 | {
|
|---|
| 255 | RTTIMESPEC Tmp;
|
|---|
| 256 | RTTimeSpecAdd(RTTimeSpecSetTimeval(&Tmp, &tv), &Drift);
|
|---|
| 257 | if (!settimeofday(RTTimeSpecGetTimeval(&Tmp, &tv), NULL))
|
|---|
| 258 | {
|
|---|
| 259 | if (g_cVerbosity >= 1)
|
|---|
| 260 | VBoxServiceVerbose(1, "settimeofday to %s\n",
|
|---|
| 261 | RTTimeToString(RTTimeExplode(&Time, &Tmp), sz, sizeof(sz)));
|
|---|
| 262 | # ifdef DEBUG
|
|---|
| 263 | if (g_cVerbosity >= 3)
|
|---|
| 264 | VBoxServiceVerbose(2, " new time %s\n",
|
|---|
| 265 | RTTimeToString(RTTimeExplode(&Time, RTTimeNow(&Tmp)), sz, sizeof(sz)));
|
|---|
| 266 | # endif
|
|---|
| 267 | cErrors = 0;
|
|---|
| 268 | }
|
|---|
| 269 | else if (cErrors++ < 10)
|
|---|
| 270 | VBoxServiceError("settimeofday failed; errno=%d: %s\n", errno, strerror(errno));
|
|---|
| 271 | }
|
|---|
| 272 | else if (cErrors++ < 10)
|
|---|
| 273 | VBoxServiceError("gettimeofday failed; errno=%d: %s\n", errno, strerror(errno));
|
|---|
| 274 | }
|
|---|
| 275 | #endif /* !RT_OS_WINDOWS */
|
|---|
| 276 | }
|
|---|
| 277 | break;
|
|---|
| 278 | }
|
|---|
| 279 | VBoxServiceVerbose(3, "%RDtimespec: latency too high (%RDtimespec) sleeping 1s\n", GuestElapsed);
|
|---|
| 280 | RTThreadSleep(1000);
|
|---|
| 281 | } while (--cTries > 0);
|
|---|
| 282 |
|
|---|
| 283 | /*
|
|---|
| 284 | * Block for a while.
|
|---|
| 285 | *
|
|---|
| 286 | * The event semaphore takes care of ignoring interruptions and it
|
|---|
| 287 | * allows us to implement service wakeup later.
|
|---|
| 288 | */
|
|---|
| 289 | if (*pfShutdown)
|
|---|
| 290 | break;
|
|---|
| 291 | int rc2 = RTSemEventMultiWait(g_TimeSyncEvent, g_TimeSyncInterval);
|
|---|
| 292 | if (*pfShutdown)
|
|---|
| 293 | break;
|
|---|
| 294 | if (rc2 != VERR_TIMEOUT && RT_FAILURE(rc2))
|
|---|
| 295 | {
|
|---|
| 296 | VBoxServiceError("RTSemEventMultiWait failed; rc2=%Rrc\n", rc2);
|
|---|
| 297 | rc = rc2;
|
|---|
| 298 | break;
|
|---|
| 299 | }
|
|---|
| 300 | }
|
|---|
| 301 |
|
|---|
| 302 | RTSemEventMultiDestroy(g_TimeSyncEvent);
|
|---|
| 303 | g_TimeSyncEvent = NIL_RTSEMEVENTMULTI;
|
|---|
| 304 | return rc;
|
|---|
| 305 | }
|
|---|
| 306 |
|
|---|
| 307 |
|
|---|
| 308 | /** @copydoc VBOXSERVICE::pfnStop */
|
|---|
| 309 | static DECLCALLBACK(void) VBoxServiceTimeSyncStop(void)
|
|---|
| 310 | {
|
|---|
| 311 | RTSemEventMultiSignal(g_TimeSyncEvent);
|
|---|
| 312 | }
|
|---|
| 313 |
|
|---|
| 314 |
|
|---|
| 315 | /** @copydoc VBOXSERVICE::pfnTerm */
|
|---|
| 316 | static DECLCALLBACK(void) VBoxServiceTimeSyncTerm(void)
|
|---|
| 317 | {
|
|---|
| 318 | RTSemEventMultiDestroy(g_TimeSyncEvent);
|
|---|
| 319 | g_TimeSyncEvent = NIL_RTSEMEVENTMULTI;
|
|---|
| 320 | }
|
|---|
| 321 |
|
|---|
| 322 |
|
|---|
| 323 | /**
|
|---|
| 324 | * The 'timesync' service description.
|
|---|
| 325 | */
|
|---|
| 326 | VBOXSERVICE g_TimeSync =
|
|---|
| 327 | {
|
|---|
| 328 | /* pszName. */
|
|---|
| 329 | "timesync",
|
|---|
| 330 | /* pszDescription. */
|
|---|
| 331 | "Time synchronization",
|
|---|
| 332 | /* pszUsage. */
|
|---|
| 333 | "[--timesync-interval <ms>] [--timesync-min-adjust <ms>] "
|
|---|
| 334 | "[--timesync-latency-factor <x>] [--time-sync-max-latency <ms>]"
|
|---|
| 335 | ,
|
|---|
| 336 | /* pszOptions. */
|
|---|
| 337 | " --timesync-interval Specifies the interval at which to synchronize the\n"
|
|---|
| 338 | " time with the host. The default is 10000 ms.\n"
|
|---|
| 339 | " --timesync-min-adjust The minimum absolute drift drift value measured\n"
|
|---|
| 340 | " in milliseconds to make adjustments for.\n"
|
|---|
| 341 | " The default is 1000 ms on OS/2 and 100 ms elsewhere.\n"
|
|---|
| 342 | " --timesync-latency-factor The factor to multiply the time query latency\n"
|
|---|
| 343 | " with to calculate the dynamic minimum adjust time.\n"
|
|---|
| 344 | " The default is 8 times.\n"
|
|---|
| 345 | " --timesync-max-latency The max host timer query latency to accpet.\n"
|
|---|
| 346 | " The default is 250 ms.\n"
|
|---|
| 347 | ,
|
|---|
| 348 | /* methods */
|
|---|
| 349 | VBoxServiceTimeSyncPreInit,
|
|---|
| 350 | VBoxServiceTimeSyncOption,
|
|---|
| 351 | VBoxServiceTimeSyncInit,
|
|---|
| 352 | VBoxServiceTimeSyncWorker,
|
|---|
| 353 | VBoxServiceTimeSyncStop,
|
|---|
| 354 | VBoxServiceTimeSyncTerm
|
|---|
| 355 | };
|
|---|
| 356 |
|
|---|
