1 /* 2 * Copyright (c) 2016, 2018, Red Hat, Inc. All rights reserved. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. 7 * 8 * This code is distributed in the hope that it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 11 * version 2 for more details (a copy is included in the LICENSE file that 12 * accompanied this code). 13 * 14 * You should have received a copy of the GNU General Public License version 15 * 2 along with this work; if not, write to the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 17 * 18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 19 * or visit www.oracle.com if you need additional information or have any 20 * questions. 21 * 22 */ 23 24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAH_GLOBALS_HPP 25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAH_GLOBALS_HPP 26 27 #include "runtime/globals.hpp" 28 29 #define SHENANDOAH_FLAGS(develop, \ 30 develop_pd, \ 31 product, \ 32 product_pd, \ 33 diagnostic, \ 34 experimental, \ 35 notproduct, \ 36 manageable, \ 37 product_rw) \ 38 \ 39 experimental(uintx, ShenandoahHeapRegionSize, 0, \ 40 "Size of the Shenandoah regions. Set to zero to detect " \ 41 "automatically.") \ 42 \ 43 experimental(uintx, ShenandoahTargetNumRegions, 2048, \ 44 "Target number of regions. We try to get around that many " \ 45 "regions, based on Shenandoah{Min,Max}RegionSize.") \ 46 \ 47 experimental(uintx, ShenandoahMinRegionSize, 256 * K, \ 48 "Minimum Shenandoah heap region size.") \ 49 \ 50 experimental(uintx, ShenandoahMaxRegionSize, 32 * M, \ 51 "Maximum Shenandoah heap region size.") \ 52 \ 53 experimental(intx, ShenandoahHumongousThreshold, 100, \ 54 "How large should the object be to get allocated in humongous " \ 55 "region, in percents of heap region size. This also caps the " \ 56 "maximum TLAB size.") \ 57 \ 58 product(ccstr, ShenandoahGCHeuristics, "adaptive", \ 59 "The heuristics to use in Shenandoah GC. Possible values:" \ 60 " *) adaptive - adapt to maintain the given amount of free heap;" \ 61 " *) static - start concurrent GC when static free heap " \ 62 " threshold and static allocation threshold are " \ 63 " tripped;" \ 64 " *) aggressive - run concurrent GC continuously, evacuate " \ 65 " everything;" \ 66 " *) compact - run GC with lower footprint target, may end up " \ 67 " doing continuous GC, evacuate lots of live " \ 68 " objects, uncommit heap aggressively;") \ 69 \ 70 product(ccstr, ShenandoahGCMode, "normal", \ 71 "The GC mode to use in Shenandoah GC. Possible values" \ 72 " *) normal - normal GC (mark-evac-update)" \ 73 " *) passive - disable concurrent GC, do stop-the-world GC") \ 74 \ 75 experimental(ccstr, ShenandoahUpdateRefsEarly, "adaptive", \ 76 "Run a separate concurrent reference updating phase after" \ 77 "concurrent evacuation. Possible values: 'on', 'off', 'adaptive'")\ 78 \ 79 experimental(uintx, ShenandoahRefProcFrequency, 5, \ 80 "How often should (weak, soft, etc) references be processed. " \ 81 "References get processed at every Nth GC cycle. Set to zero " \ 82 "to disable reference processing.") \ 83 \ 84 experimental(uintx, ShenandoahUnloadClassesFrequency, 5, \ 85 "How often should classes get unloaded. " \ 86 "Class unloading is performed at every Nth GC cycle. " \ 87 "Set to zero to disable class unloading during concurrent GC.") \ 88 \ 89 experimental(uintx, ShenandoahGarbageThreshold, 60, \ 90 "Sets the percentage of garbage a region need to contain before " \ 91 "it can be marked for collection. Does not apply to all " \ 92 "heuristics.") \ 93 \ 94 experimental(uintx, ShenandoahFreeThreshold, 10, \ 95 "Set the percentage of free heap at which a GC cycle is started. "\ 96 "Does not apply to all heuristics.") \ 97 \ 98 experimental(uintx, ShenandoahInitFreeThreshold, 70, \ 99 "Initial remaining free heap threshold for learning steps in " \ 100 "heuristics. In percents of total heap size. Does not apply to " \ 101 "all heuristics.") \ 102 \ 103 experimental(uintx, ShenandoahMinFreeThreshold, 10, \ 104 "Minimum remaining free space threshold, after which collection " \ 105 "definitely triggers. Does not apply to all heuristics.") \ 106 \ 107 experimental(uintx, ShenandoahAllocationThreshold, 0, \ 108 "Set percentage of memory allocated since last GC cycle before " \ 109 "a new GC cycle can be started. Set to zero to effectively " \ 110 "disable.") \ 111 \ 112 experimental(uintx, ShenandoahLearningSteps, 5, \ 113 "Number of GC cycles to run in order to learn application " \ 114 "and GC performance for adaptive heuristics.") \ 115 \ 116 experimental(uintx, ShenandoahImmediateThreshold, 90, \ 117 "If mark identifies more than this much immediate garbage " \ 118 "regions, it shall recycle them, and shall not continue the " \ 119 "rest of the GC cycle. The value is in percents of total " \ 120 "number of candidate regions for collection set. Setting this " \ 121 "threshold to 100% effectively disables this shortcut.") \ 122 \ 123 experimental(uintx, ShenandoahMergeUpdateRefsMinGap, 100, \ 124 "If GC is currently running in separate update-refs mode " \ 125 "this numbers gives the threshold when to switch to " \ 126 "merged update-refs mode. Number is percentage relative to" \ 127 "duration(marking)+duration(update-refs).") \ 128 \ 129 experimental(uintx, ShenandoahMergeUpdateRefsMaxGap, 200, \ 130 "If GC is currently running in merged update-refs mode " \ 131 "this numbers gives the threshold when to switch to " \ 132 "separate update-refs mode. Number is percentage relative " \ 133 "to duration(marking)+duration(update-refs).") \ 134 \ 135 experimental(uintx, ShenandoahGuaranteedGCInterval, 5*60*1000, \ 136 "Adaptive and dynamic heuristics would guarantee a GC cycle " \ 137 "at least with this interval. This is useful when large idle" \ 138 " intervals are present, where GC can run without stealing " \ 139 "time from active application. Time is in milliseconds.") \ 140 \ 141 experimental(bool, ShenandoahAlwaysClearSoftRefs, false, \ 142 "Clear soft references always, instead of using any smart " \ 143 "cleanup policy. This minimizes footprint at expense of more " \ 144 "softref churn in applications.") \ 145 \ 146 experimental(bool, ShenandoahUncommit, true, \ 147 "Allow Shenandoah to uncommit unused memory.") \ 148 \ 149 experimental(uintx, ShenandoahUncommitDelay, 5*60*1000, \ 150 "Shenandoah would start to uncommit memory for regions that were" \ 151 " not used for more than this time. First use after that would " \ 152 "incur allocation stalls. Actively used regions would never be " \ 153 "uncommitted, because they never decay. Time is in milliseconds." \ 154 "Setting this delay to 0 effectively makes Shenandoah to " \ 155 "uncommit the regions almost immediately.") \ 156 \ 157 experimental(bool, ShenandoahRegionSampling, false, \ 158 "Turns on heap region sampling via JVMStat") \ 159 \ 160 experimental(int, ShenandoahRegionSamplingRate, 40, \ 161 "Sampling rate for heap region sampling. " \ 162 "Number of milliseconds between samples") \ 163 \ 164 experimental(uintx, ShenandoahControlIntervalMin, 1, \ 165 "The minumum sleep interval for control loop that drives " \ 166 "the cycles. Lower values would increase GC responsiveness " \ 167 "to changing heap conditions, at the expense of higher perf " \ 168 "overhead. Time is in milliseconds.") \ 169 \ 170 experimental(uintx, ShenandoahControlIntervalMax, 10, \ 171 "The maximum sleep interval for control loop that drives " \ 172 "the cycles. Lower values would increase GC responsiveness " \ 173 "to changing heap conditions, at the expense of higher perf " \ 174 "overhead. Time is in milliseconds.") \ 175 \ 176 experimental(uintx, ShenandoahControlIntervalAdjustPeriod, 1000, \ 177 "The time period for one step in control loop interval " \ 178 "adjustment. Lower values make adjustments faster, at the " \ 179 "expense of higher perf overhead. Time is in milliseconds.") \ 180 \ 181 experimental(bool, ShenandoahCriticalControlThreadPriority, false, \ 182 "Shenandoah control thread runs at critical scheduling priority.")\ 183 \ 184 diagnostic(bool, ShenandoahVerify, false, \ 185 "Verify the Shenandoah garbage collector") \ 186 \ 187 diagnostic(intx, ShenandoahVerifyLevel, 4, \ 188 "Shenandoah verification level: " \ 189 "0 = basic heap checks; " \ 190 "1 = previous level, plus basic region checks; " \ 191 "2 = previous level, plus all roots; " \ 192 "3 = previous level, plus all reachable objects; " \ 193 "4 = previous level, plus all marked objects") \ 194 \ 195 diagnostic(bool, ShenandoahElasticTLAB, true, \ 196 "Use Elastic TLABs with Shenandoah") \ 197 \ 198 diagnostic(bool, ShenandoahAllowMixedAllocs, true, \ 199 "Allow mixing mutator and collector allocations in a single " \ 200 "region") \ 201 \ 202 experimental(uintx, ShenandoahAllocSpikeFactor, 5, \ 203 "The amount of heap space to reserve for absorbing the " \ 204 "allocation spikes. Larger value wastes more memory in " \ 205 "non-emergency cases, but provides more safety in emergency " \ 206 "cases. In percents of total heap size.") \ 207 \ 208 experimental(uintx, ShenandoahEvacReserve, 5, \ 209 "Maximum amount of free space to reserve for evacuation. " \ 210 "Larger values make GC more aggressive, while leaving less " \ 211 "headroom for application to allocate in. " \ 212 "In percents of total heap size.") \ 213 \ 214 experimental(double, ShenandoahEvacWaste, 1.2, \ 215 "How much waste evacuations produce within the reserved " \ 216 "space. Larger values make evacuations more resilient " \ 217 "against allocation failures, at expense of smaller csets " \ 218 "on each cycle.") \ 219 \ 220 experimental(bool, ShenandoahEvacReserveOverflow, true, \ 221 "Allow evacuations to overflow the reserved space. " \ 222 "Enabling it will make evacuations more resilient when " \ 223 "evacuation reserve/waste is incorrect, at the risk that " \ 224 "application allocations run out of memory too early.") \ 225 \ 226 diagnostic(bool, ShenandoahAllocationTrace, false, \ 227 "Trace allocation latencies and stalls. Can be expensive when " \ 228 "lots of allocations happen, and may introduce scalability " \ 229 "bottlenecks.") \ 230 \ 231 diagnostic(intx, ShenandoahAllocationStallThreshold, 10000, \ 232 "When allocation tracing is enabled, the allocation stalls " \ 233 "larger than this threshold would be reported as warnings. " \ 234 "Time is in microseconds.") \ 235 \ 236 experimental(uintx, ShenandoahEvacAssist, 10, \ 237 "How many objects to evacuate on LRB assist path. " \ 238 "Use zero to disable.") \ 239 \ 240 experimental(bool, ShenandoahPacing, true, \ 241 "Pace application allocations to give GC chance to start " \ 242 "and complete before allocation failure is reached.") \ 243 \ 244 experimental(uintx, ShenandoahPacingMaxDelay, 10, \ 245 "Max delay for pacing application allocations. " \ 246 "Time is in milliseconds.") \ 247 \ 248 experimental(uintx, ShenandoahPacingIdleSlack, 2, \ 249 "Percent of heap counted as non-taxable allocations during idle. "\ 250 "Larger value makes the pacing milder during idle phases, " \ 251 "requiring less rendezvous with control thread. Lower value " \ 252 "makes the pacing control less responsive to out-of-cycle allocs.")\ 253 \ 254 experimental(uintx, ShenandoahPacingCycleSlack, 10, \ 255 "Percent of free space taken as non-taxable allocations during " \ 256 "the GC cycle. Larger value makes the pacing milder at the " \ 257 "beginning of the GC cycle. Lower value makes the pacing less " \ 258 "uniform during the cycle.") \ 259 \ 260 experimental(double, ShenandoahPacingSurcharge, 1.1, \ 261 "Additional pacing tax surcharge to help unclutter the heap. " \ 262 "Larger values makes the pacing more aggressive. Lower values " \ 263 "risk GC cycles finish with less memory than were available at " \ 264 "the beginning of it.") \ 265 \ 266 experimental(uintx, ShenandoahCriticalFreeThreshold, 1, \ 267 "Percent of heap that needs to be free after recovery cycles, " \ 268 "either Degenerated or Full GC. If this much space is not " \ 269 "available, next recovery step would triggered.") \ 270 \ 271 diagnostic(bool, ShenandoahDegeneratedGC, true, \ 272 "Use Degenerated GC as the graceful degradation step. Disabling " \ 273 "this leads to degradation to Full GC") \ 274 \ 275 experimental(uintx, ShenandoahFullGCThreshold, 3, \ 276 "How many back-to-back Degenerated GCs to do before triggering " \ 277 "a Full GC.") \ 278 \ 279 experimental(bool, ShenandoahImplicitGCInvokesConcurrent, false, \ 280 "Should internally-caused GCs invoke concurrent cycles, or go to" \ 281 "stop-the-world (degenerated/full)?") \ 282 \ 283 diagnostic(bool, ShenandoahHumongousMoves, true, \ 284 "Allow moving humongous regions. This makes GC more resistant " \ 285 "to external fragmentation that may otherwise fail other " \ 286 "humongous allocations, at the expense of higher GC copying " \ 287 "costs. Currently affects stop-the-world (full) cycle only.") \ 288 \ 289 diagnostic(bool, ShenandoahOOMDuringEvacALot, false, \ 290 "Simulate OOM during evacuation frequently.") \ 291 \ 292 diagnostic(bool, ShenandoahAllocFailureALot, false, \ 293 "Make lots of artificial allocation failures.") \ 294 \ 295 diagnostic(bool, ShenandoahTerminationTrace, false, \ 296 "Tracing task termination timings") \ 297 \ 298 diagnostic(bool, ShenandoahAlwaysPreTouch, false, \ 299 "Pre-touch heap memory, overrides global AlwaysPreTouch") \ 300 \ 301 experimental(intx, ShenandoahMarkScanPrefetch, 32, \ 302 "How many objects to prefetch ahead when traversing mark bitmaps."\ 303 "Set to 0 to disable prefetching.") \ 304 \ 305 experimental(uintx, ShenandoahMarkLoopStride, 1000, \ 306 "How many items are processed during one marking step") \ 307 \ 308 experimental(uintx, ShenandoahParallelRegionStride, 1024, \ 309 "How many regions are processed in one stride during parallel " \ 310 "iteration.") \ 311 \ 312 experimental(intx, ShenandoahSATBBufferSize, 1 * K, \ 313 "Number of entries in an SATB log buffer.") \ 314 \ 315 experimental(uintx, ShenandoahSATBBufferFlushInterval, 100, \ 316 "Forcefully flush non-empty SATB buffers at this interval. " \ 317 "Time is in milliseconds.") \ 318 \ 319 experimental(bool, ShenandoahPreclean, true, \ 320 "Do concurrent preclean phase before final mark: process " \ 321 "definitely alive references to avoid dealing with them during " \ 322 "pause.") \ 323 \ 324 diagnostic(bool, ShenandoahSATBBarrier, true, \ 325 "Turn on/off SATB barriers in Shenandoah") \ 326 \ 327 diagnostic(bool, ShenandoahCASBarrier, true, \ 328 "Turn on/off CAS barriers in Shenandoah") \ 329 \ 330 diagnostic(bool, ShenandoahCloneBarrier, true, \ 331 "Turn on/off clone barriers in Shenandoah") \ 332 \ 333 diagnostic(bool, ShenandoahLoadRefBarrier, true, \ 334 "Turn on/off load-reference barriers in Shenandoah") \ 335 \ 336 experimental(bool, ShenandoahConcurrentScanCodeRoots, true, \ 337 "Scan code roots concurrently, instead of during a pause") \ 338 \ 339 experimental(uintx, ShenandoahCodeRootsStyle, 2, \ 340 "Use this style to scan code cache:" \ 341 " 0 - sequential iterator;" \ 342 " 1 - parallel iterator;" \ 343 " 2 - parallel iterator with cset filters;") \ 344 \ 345 diagnostic(bool, ShenandoahOptimizeStaticFinals, true, \ 346 "Optimize barriers on static final fields. " \ 347 "Turn it off for maximum compatibility with reflection or JNI " \ 348 "code that manipulates final fields.") \ 349 \ 350 experimental(bool, ShenandoahCommonGCStateLoads, false, \ 351 "Enable commonming for GC state loads in generated code.") \ 352 \ 353 develop(bool, ShenandoahVerifyOptoBarriers, false, \ 354 "Verify no missing barriers in c2") \ 355 \ 356 product(bool, ShenandoahLogTrace, false, \ 357 "Turns on logging in Shenandoah at trace level. ") \ 358 \ 359 product(bool, ShenandoahLogDebug, false, \ 360 "Turns on logging in Shenandoah at debug level. ") \ 361 \ 362 product(bool, ShenandoahLogInfo, false, \ 363 "Turns on logging in Shenandoah at info level. ") \ 364 \ 365 product(bool, ShenandoahLogWarning, false, \ 366 "Turns on logging in Shenandoah at warning level. ") \ 367 \ 368 369 SHENANDOAH_FLAGS(DECLARE_DEVELOPER_FLAG, \ 370 DECLARE_PD_DEVELOPER_FLAG, \ 371 DECLARE_PRODUCT_FLAG, \ 372 DECLARE_PD_PRODUCT_FLAG, \ 373 DECLARE_DIAGNOSTIC_FLAG, \ 374 DECLARE_EXPERIMENTAL_FLAG, \ 375 DECLARE_NOTPRODUCT_FLAG, \ 376 DECLARE_MANAGEABLE_FLAG, \ 377 DECLARE_PRODUCT_RW_FLAG) 378 379 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAH_GLOBALS_HPP