base/allocator/partition_alloc_features.cc - platform/external/cronet - Git at Google

 // Copyright 2020 The Chromium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "base/allocator/partition_alloc_features.h"

 #include "base/allocator/miracle_parameter.h"
 #include "base/allocator/partition_allocator/src/partition_alloc/partition_alloc_base/time/time.h"
 #include "base/allocator/partition_allocator/src/partition_alloc/partition_alloc_buildflags.h"
 #include "base/allocator/partition_allocator/src/partition_alloc/partition_root.h"
 #include "base/allocator/partition_allocator/src/partition_alloc/thread_cache.h"
 #include "base/base_export.h"
 #include "base/feature_list.h"
 #include "base/features.h"
 #include "base/metrics/field_trial_params.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "build/chromecast_buildflags.h"
 #include "build/chromeos_buildflags.h"

 namespace base {
 namespace features {

 BASE_FEATURE(kPartitionAllocUnretainedDanglingPtr,
              "PartitionAllocUnretainedDanglingPtr",
              FEATURE_ENABLED_BY_DEFAULT);

 constexpr FeatureParam<UnretainedDanglingPtrMode>::Option
     kUnretainedDanglingPtrModeOption[] = {
         {UnretainedDanglingPtrMode::kCrash, "crash"},
         {UnretainedDanglingPtrMode::kDumpWithoutCrashing,
          "dump_without_crashing"},
 };
 const base::FeatureParam<UnretainedDanglingPtrMode>
     kUnretainedDanglingPtrModeParam = {
         &kPartitionAllocUnretainedDanglingPtr,
         "mode",
         UnretainedDanglingPtrMode::kDumpWithoutCrashing,
         &kUnretainedDanglingPtrModeOption,
 };

 BASE_FEATURE(kPartitionAllocDanglingPtr,
              "PartitionAllocDanglingPtr",
 #if BUILDFLAG(ENABLE_DANGLING_RAW_PTR_FEATURE_FLAG) ||                   \
     (BUILDFLAG(ENABLE_DANGLING_RAW_PTR_CHECKS) && BUILDFLAG(IS_LINUX) && \
      !defined(OFFICIAL_BUILD) && (!defined(NDEBUG) || DCHECK_IS_ON()))
              FEATURE_ENABLED_BY_DEFAULT
 #else
              FEATURE_DISABLED_BY_DEFAULT
 #endif
 );

 constexpr FeatureParam<DanglingPtrMode>::Option kDanglingPtrModeOption[] = {
     {DanglingPtrMode::kCrash, "crash"},
     {DanglingPtrMode::kLogOnly, "log_only"},
 };
 const base::FeatureParam<DanglingPtrMode> kDanglingPtrModeParam{
     &kPartitionAllocDanglingPtr,
     "mode",
     DanglingPtrMode::kCrash,
     &kDanglingPtrModeOption,
 };
 constexpr FeatureParam<DanglingPtrType>::Option kDanglingPtrTypeOption[] = {
     {DanglingPtrType::kAll, "all"},
     {DanglingPtrType::kCrossTask, "cross_task"},
 };
 const base::FeatureParam<DanglingPtrType> kDanglingPtrTypeParam{
     &kPartitionAllocDanglingPtr,
     "type",
     DanglingPtrType::kAll,
     &kDanglingPtrTypeOption,
 };

 #if BUILDFLAG(USE_STARSCAN)
 // If enabled, PCScan is turned on by default for all partitions that don't
 // disable it explicitly.
 BASE_FEATURE(kPartitionAllocPCScan,
              "PartitionAllocPCScan",
              FEATURE_DISABLED_BY_DEFAULT);
 #endif  // BUILDFLAG(USE_STARSCAN)

 #if BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
 // If enabled, PCScan is turned on only for the browser's malloc partition.
 BASE_FEATURE(kPartitionAllocPCScanBrowserOnly,
              "PartitionAllocPCScanBrowserOnly",
              FEATURE_DISABLED_BY_DEFAULT);

 // If enabled, PCScan is turned on only for the renderer's malloc partition.
 BASE_FEATURE(kPartitionAllocPCScanRendererOnly,
              "PartitionAllocPCScanRendererOnly",
              FEATURE_DISABLED_BY_DEFAULT);

 // Use a larger maximum thread cache cacheable bucket size.
 BASE_FEATURE(kPartitionAllocLargeThreadCacheSize,
              "PartitionAllocLargeThreadCacheSize",
              FEATURE_ENABLED_BY_DEFAULT);

 MIRACLE_PARAMETER_FOR_INT(
     GetPartitionAllocLargeThreadCacheSizeValue,
     kPartitionAllocLargeThreadCacheSize,
     "PartitionAllocLargeThreadCacheSizeValue",
     ::partition_alloc::ThreadCacheLimits::kLargeSizeThreshold)

 MIRACLE_PARAMETER_FOR_INT(
     GetPartitionAllocLargeThreadCacheSizeValueForLowRAMAndroid,
     kPartitionAllocLargeThreadCacheSize,
     "PartitionAllocLargeThreadCacheSizeValueForLowRAMAndroid",
     ::partition_alloc::ThreadCacheLimits::kDefaultSizeThreshold)

 BASE_FEATURE(kPartitionAllocLargeEmptySlotSpanRing,
              "PartitionAllocLargeEmptySlotSpanRing",
              FEATURE_DISABLED_BY_DEFAULT);

 BASE_FEATURE(kPartitionAllocSchedulerLoopQuarantine,
              "PartitionAllocSchedulerLoopQuarantine",
              FEATURE_DISABLED_BY_DEFAULT);
 // Scheduler Loop Quarantine's capacity in bytes.
 const base::FeatureParam<int> kPartitionAllocSchedulerLoopQuarantineCapacity{
     &kPartitionAllocSchedulerLoopQuarantine,
     "PartitionAllocSchedulerLoopQuarantineCapacity", 0};

 BASE_FEATURE(kPartitionAllocZappingByFreeFlags,
              "PartitionAllocZappingByFreeFlags",
              FEATURE_DISABLED_BY_DEFAULT);
 #endif  // BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)

 BASE_FEATURE(kPartitionAllocBackupRefPtr,
              "PartitionAllocBackupRefPtr",
 #if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_WIN) || BUILDFLAG(IS_MAC) || \
     BUILDFLAG(IS_CHROMEOS_ASH) || BUILDFLAG(IS_CHROMEOS_LACROS) ||     \
     (BUILDFLAG(IS_LINUX) && !BUILDFLAG(IS_CASTOS)) ||                  \
     BUILDFLAG(ENABLE_BACKUP_REF_PTR_FEATURE_FLAG)
              FEATURE_ENABLED_BY_DEFAULT
 #else
              FEATURE_DISABLED_BY_DEFAULT
 #endif
 );

 BASE_EXPORT BASE_DECLARE_FEATURE(kPartitionAllocBackupRefPtrForAsh);
 BASE_FEATURE(kPartitionAllocBackupRefPtrForAsh,
              "PartitionAllocBackupRefPtrForAsh",
              FEATURE_ENABLED_BY_DEFAULT);

 constexpr FeatureParam<BackupRefPtrEnabledProcesses>::Option
     kBackupRefPtrEnabledProcessesOptions[] = {
         {BackupRefPtrEnabledProcesses::kBrowserOnly, "browser-only"},
         {BackupRefPtrEnabledProcesses::kBrowserAndRenderer,
          "browser-and-renderer"},
         {BackupRefPtrEnabledProcesses::kNonRenderer, "non-renderer"},
         {BackupRefPtrEnabledProcesses::kAllProcesses, "all-processes"}};

 const base::FeatureParam<BackupRefPtrEnabledProcesses>
     kBackupRefPtrEnabledProcessesParam{
         &kPartitionAllocBackupRefPtr, "enabled-processes",
         BackupRefPtrEnabledProcesses::kNonRenderer,
         &kBackupRefPtrEnabledProcessesOptions};

 constexpr FeatureParam<BackupRefPtrRefCountSize>::Option
     kBackupRefPtrRefCountSizeOptions[] = {
         {BackupRefPtrRefCountSize::kNatural, "natural"},
         {BackupRefPtrRefCountSize::k4B, "4B"},
         {BackupRefPtrRefCountSize::k8B, "8B"},
         {BackupRefPtrRefCountSize::k16B, "16B"}};

 const base::FeatureParam<BackupRefPtrRefCountSize>
     kBackupRefPtrRefCountSizeParam{
         &kPartitionAllocBackupRefPtr, "ref-count-size",
         BackupRefPtrRefCountSize::kNatural, &kBackupRefPtrRefCountSizeOptions};

 // Map -with-memory-reclaimer modes onto their counterpars without the suffix.
 // They are the same, as memory reclaimer is now controlled independently.
 // However, we need to keep both option strings, as there is a long tail of
 // clients that may have an old field trial config, which used these modes.
 //
 // DO NOT USE -with-memory-reclaimer modes in new configs!
 constexpr FeatureParam<BackupRefPtrMode>::Option kBackupRefPtrModeOptions[] = {
     {BackupRefPtrMode::kDisabled, "disabled"},
     {BackupRefPtrMode::kEnabled, "enabled"},
     {BackupRefPtrMode::kEnabled, "enabled-with-memory-reclaimer"},
     {BackupRefPtrMode::kDisabledButSplitPartitions2Way,
      "disabled-but-2-way-split"},
     {BackupRefPtrMode::kDisabledButSplitPartitions2Way,
      "disabled-but-2-way-split-with-memory-reclaimer"},
     {BackupRefPtrMode::kDisabledButSplitPartitions3Way,
      "disabled-but-3-way-split"},
 };

 const base::FeatureParam<BackupRefPtrMode> kBackupRefPtrModeParam{
     &kPartitionAllocBackupRefPtr, "brp-mode", BackupRefPtrMode::kEnabled,
     &kBackupRefPtrModeOptions};

 BASE_FEATURE(kPartitionAllocMemoryTagging,
              "PartitionAllocMemoryTagging",
              FEATURE_DISABLED_BY_DEFAULT);

 constexpr FeatureParam<MemtagMode>::Option kMemtagModeOptions[] = {
     {MemtagMode::kSync, "sync"},
     {MemtagMode::kAsync, "async"}};

 const base::FeatureParam<MemtagMode> kMemtagModeParam{
     &kPartitionAllocMemoryTagging, "memtag-mode", MemtagMode::kAsync,
     &kMemtagModeOptions};

 constexpr FeatureParam<MemoryTaggingEnabledProcesses>::Option
     kMemoryTaggingEnabledProcessesOptions[] = {
         {MemoryTaggingEnabledProcesses::kBrowserOnly, "browser-only"},
         {MemoryTaggingEnabledProcesses::kNonRenderer, "non-renderer"},
         {MemoryTaggingEnabledProcesses::kAllProcesses, "all-processes"}};

 const base::FeatureParam<MemoryTaggingEnabledProcesses>
     kMemoryTaggingEnabledProcessesParam{
         &kPartitionAllocMemoryTagging, "enabled-processes",
         MemoryTaggingEnabledProcesses::kBrowserOnly,
         &kMemoryTaggingEnabledProcessesOptions};

 BASE_FEATURE(kKillPartitionAllocMemoryTagging,
              "KillPartitionAllocMemoryTagging",
              FEATURE_DISABLED_BY_DEFAULT);

 BASE_EXPORT BASE_DECLARE_FEATURE(kPartitionAllocPermissiveMte);
 BASE_FEATURE(kPartitionAllocPermissiveMte,
              "PartitionAllocPermissiveMte",
              FEATURE_ENABLED_BY_DEFAULT);

 const base::FeatureParam<bool> kBackupRefPtrAsanEnableDereferenceCheckParam{
     &kPartitionAllocBackupRefPtr, "asan-enable-dereference-check", true};
 const base::FeatureParam<bool> kBackupRefPtrAsanEnableExtractionCheckParam{
     &kPartitionAllocBackupRefPtr, "asan-enable-extraction-check",
     false};  // Not much noise at the moment to enable by default.
 const base::FeatureParam<bool> kBackupRefPtrAsanEnableInstantiationCheckParam{
     &kPartitionAllocBackupRefPtr, "asan-enable-instantiation-check", true};

 // If enabled, switches the bucket distribution to a denser one.
 //
 // We enable this by default everywhere except for 32-bit Android, since we saw
 // regressions there.
 BASE_FEATURE(kPartitionAllocUseDenserDistribution,
              "PartitionAllocUseDenserDistribution",
 #if BUILDFLAG(IS_ANDROID) && defined(ARCH_CPU_32_BITS)
              FEATURE_DISABLED_BY_DEFAULT
 #else
              FEATURE_ENABLED_BY_DEFAULT
 #endif  // BUILDFLAG(IS_ANDROID) && defined(ARCH_CPU_32_BITS)
 );
 const base::FeatureParam<BucketDistributionMode>::Option
     kPartitionAllocBucketDistributionOption[] = {
         {BucketDistributionMode::kDefault, "default"},
         {BucketDistributionMode::kDenser, "denser"},
 };
 const base::FeatureParam<BucketDistributionMode>
     kPartitionAllocBucketDistributionParam {
   &kPartitionAllocUseDenserDistribution, "mode",
 #if BUILDFLAG(IS_ANDROID) && defined(ARCH_CPU_32_BITS)
       BucketDistributionMode::kDefault,
 #else
       BucketDistributionMode::kDenser,
 #endif  // BUILDFLAG(IS_ANDROID) && defined(ARCH_CPU_32_BITS)
       &kPartitionAllocBucketDistributionOption
 };

 BASE_FEATURE(kPartitionAllocMemoryReclaimer,
              "PartitionAllocMemoryReclaimer",
              FEATURE_ENABLED_BY_DEFAULT);
 const base::FeatureParam<TimeDelta> kPartitionAllocMemoryReclaimerInterval = {
     &kPartitionAllocMemoryReclaimer, "interval",
     TimeDelta(),  // Defaults to zero.
 };

 // Configures whether we set a lower limit for renderers that do not have a main
 // frame, similar to the limit that is already done for backgrounded renderers.
 BASE_FEATURE(kLowerPAMemoryLimitForNonMainRenderers,
              "LowerPAMemoryLimitForNonMainRenderers",
              FEATURE_DISABLED_BY_DEFAULT);

 // If enabled, switches PCScan scheduling to a mutator-aware scheduler. Does not
 // affect whether PCScan is enabled itself.
 BASE_FEATURE(kPartitionAllocPCScanMUAwareScheduler,
              "PartitionAllocPCScanMUAwareScheduler",
              FEATURE_ENABLED_BY_DEFAULT);

 // If enabled, PCScan frees unconditionally all quarantined objects.
 // This is a performance testing feature.
 BASE_FEATURE(kPartitionAllocPCScanImmediateFreeing,
              "PartitionAllocPCScanImmediateFreeing",
              FEATURE_DISABLED_BY_DEFAULT);

 // If enabled, PCScan clears eagerly (synchronously) on free().
 BASE_FEATURE(kPartitionAllocPCScanEagerClearing,
              "PartitionAllocPCScanEagerClearing",
              FEATURE_DISABLED_BY_DEFAULT);

 // In addition to heap, scan also the stack of the current mutator.
 BASE_FEATURE(kPartitionAllocPCScanStackScanning,
              "PartitionAllocPCScanStackScanning",
 #if BUILDFLAG(PCSCAN_STACK_SUPPORTED)
              FEATURE_ENABLED_BY_DEFAULT
 #else
              FEATURE_DISABLED_BY_DEFAULT
 #endif  // BUILDFLAG(PCSCAN_STACK_SUPPORTED)
 );

 BASE_FEATURE(kPartitionAllocDCScan,
              "PartitionAllocDCScan",
              FEATURE_DISABLED_BY_DEFAULT);

 // Whether to straighten free lists for larger slot spans in PurgeMemory() ->
 // ... -> PartitionPurgeSlotSpan().
 BASE_FEATURE(kPartitionAllocStraightenLargerSlotSpanFreeLists,
              "PartitionAllocStraightenLargerSlotSpanFreeLists",
              FEATURE_ENABLED_BY_DEFAULT);
 const base::FeatureParam<
     partition_alloc::StraightenLargerSlotSpanFreeListsMode>::Option
     kPartitionAllocStraightenLargerSlotSpanFreeListsModeOption[] = {
         {partition_alloc::StraightenLargerSlotSpanFreeListsMode::
              kOnlyWhenUnprovisioning,
          "only-when-unprovisioning"},
         {partition_alloc::StraightenLargerSlotSpanFreeListsMode::kAlways,
          "always"},
 };
 const base::FeatureParam<partition_alloc::StraightenLargerSlotSpanFreeListsMode>
     kPartitionAllocStraightenLargerSlotSpanFreeListsMode = {
         &kPartitionAllocStraightenLargerSlotSpanFreeLists,
         "mode",
         partition_alloc::StraightenLargerSlotSpanFreeListsMode::
             kOnlyWhenUnprovisioning,
         &kPartitionAllocStraightenLargerSlotSpanFreeListsModeOption,
 };

 // Whether to sort free lists for smaller slot spans in PurgeMemory().
 BASE_FEATURE(kPartitionAllocSortSmallerSlotSpanFreeLists,
              "PartitionAllocSortSmallerSlotSpanFreeLists",
              FEATURE_ENABLED_BY_DEFAULT);

 // Whether to sort the active slot spans in PurgeMemory().
 BASE_FEATURE(kPartitionAllocSortActiveSlotSpans,
              "PartitionAllocSortActiveSlotSpans",
              FEATURE_DISABLED_BY_DEFAULT);

 #if BUILDFLAG(IS_WIN)
 // Whether to retry allocations when commit fails.
 BASE_FEATURE(kPageAllocatorRetryOnCommitFailure,
              "PageAllocatorRetryOnCommitFailure",
              FEATURE_DISABLED_BY_DEFAULT);
 #endif

 #if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_CHROMEOS)
 // A parameter to exclude or not exclude PartitionAllocSupport from
 // PartialLowModeOnMidRangeDevices. This is used to see how it affects
 // renderer performances, e.g. blink_perf.parser benchmark.
 // The feature: kPartialLowEndModeOnMidRangeDevices is defined in
 // //base/features.cc. Since the following feature param is related to
 // PartitionAlloc, define the param here.
 const FeatureParam<bool> kPartialLowEndModeExcludePartitionAllocSupport{
     &kPartialLowEndModeOnMidRangeDevices, "exclude-partition-alloc-support",
     false};
 #endif

 BASE_FEATURE(kEnableConfigurableThreadCacheMultiplier,
              "EnableConfigurableThreadCacheMultiplier",
              base::FEATURE_DISABLED_BY_DEFAULT);

 MIRACLE_PARAMETER_FOR_DOUBLE(GetThreadCacheMultiplier,
                              kEnableConfigurableThreadCacheMultiplier,
                              "ThreadCacheMultiplier",
                              2.)

 MIRACLE_PARAMETER_FOR_DOUBLE(GetThreadCacheMultiplierForAndroid,
                              kEnableConfigurableThreadCacheMultiplier,
                              "ThreadCacheMultiplierForAndroid",
                              1.)

 constexpr partition_alloc::internal::base::TimeDelta ToPartitionAllocTimeDelta(
     base::TimeDelta time_delta) {
   return partition_alloc::internal::base::Microseconds(
       time_delta.InMicroseconds());
 }

 constexpr base::TimeDelta FromPartitionAllocTimeDelta(
     partition_alloc::internal::base::TimeDelta time_delta) {
   return base::Microseconds(time_delta.InMicroseconds());
 }

 BASE_FEATURE(kEnableConfigurableThreadCachePurgeInterval,
              "EnableConfigurableThreadCachePurgeInterval",
              base::FEATURE_DISABLED_BY_DEFAULT);

 MIRACLE_PARAMETER_FOR_TIME_DELTA(
     GetThreadCacheMinPurgeIntervalValue,
     kEnableConfigurableThreadCachePurgeInterval,
     "ThreadCacheMinPurgeInterval",
     FromPartitionAllocTimeDelta(partition_alloc::kMinPurgeInterval))

 MIRACLE_PARAMETER_FOR_TIME_DELTA(
     GetThreadCacheMaxPurgeIntervalValue,
     kEnableConfigurableThreadCachePurgeInterval,
     "ThreadCacheMaxPurgeInterval",
     FromPartitionAllocTimeDelta(partition_alloc::kMaxPurgeInterval))

 MIRACLE_PARAMETER_FOR_TIME_DELTA(
     GetThreadCacheDefaultPurgeIntervalValue,
     kEnableConfigurableThreadCachePurgeInterval,
     "ThreadCacheDefaultPurgeInterval",
     FromPartitionAllocTimeDelta(partition_alloc::kDefaultPurgeInterval))

 const partition_alloc::internal::base::TimeDelta
 GetThreadCacheMinPurgeInterval() {
   return ToPartitionAllocTimeDelta(GetThreadCacheMinPurgeIntervalValue());
 }

 const partition_alloc::internal::base::TimeDelta
 GetThreadCacheMaxPurgeInterval() {
   return ToPartitionAllocTimeDelta(GetThreadCacheMaxPurgeIntervalValue());
 }

 const partition_alloc::internal::base::TimeDelta
 GetThreadCacheDefaultPurgeInterval() {
   return ToPartitionAllocTimeDelta(GetThreadCacheDefaultPurgeIntervalValue());
 }

 BASE_FEATURE(kEnableConfigurableThreadCacheMinCachedMemoryForPurging,
              "EnableConfigurableThreadCacheMinCachedMemoryForPurging",
              base::FEATURE_DISABLED_BY_DEFAULT);

 MIRACLE_PARAMETER_FOR_INT(
     GetThreadCacheMinCachedMemoryForPurgingBytes,
     kEnableConfigurableThreadCacheMinCachedMemoryForPurging,
     "ThreadCacheMinCachedMemoryForPurgingBytes",
     partition_alloc::kMinCachedMemoryForPurgingBytes)

 // An apparent quarantine leak in the buffer partition unacceptably
 // bloats memory when MiraclePtr is enabled in the renderer process.
 // We believe we have found and patched the leak, but out of an
 // abundance of caution, we provide this toggle that allows us to
 // wholly disable MiraclePtr in the buffer partition, if necessary.
 //
 // TODO(crbug.com/1444624): this is unneeded once
 // MiraclePtr-for-Renderer launches.
 BASE_FEATURE(kPartitionAllocDisableBRPInBufferPartition,
              "PartitionAllocDisableBRPInBufferPartition",
              FEATURE_DISABLED_BY_DEFAULT);

 #if BUILDFLAG(USE_FREELIST_POOL_OFFSETS)
 BASE_FEATURE(kUsePoolOffsetFreelists,
              "PartitionAllocUsePoolOffsetFreelists",
              base::FEATURE_DISABLED_BY_DEFAULT);
 #endif

 }  // namespace features
 }  // namespace base
	// Copyright 2020 The Chromium Authors
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "base/allocator/partition_alloc_features.h"

	#include "base/allocator/miracle_parameter.h"
	#include "base/allocator/partition_allocator/src/partition_alloc/partition_alloc_base/time/time.h"
	#include "base/allocator/partition_allocator/src/partition_alloc/partition_alloc_buildflags.h"
	#include "base/allocator/partition_allocator/src/partition_alloc/partition_root.h"
	#include "base/allocator/partition_allocator/src/partition_alloc/thread_cache.h"
	#include "base/base_export.h"
	#include "base/feature_list.h"
	#include "base/features.h"
	#include "base/metrics/field_trial_params.h"
	#include "base/time/time.h"
	#include "build/build_config.h"
	#include "build/chromecast_buildflags.h"
	#include "build/chromeos_buildflags.h"

	namespace base {
	namespace features {

	BASE_FEATURE(kPartitionAllocUnretainedDanglingPtr,
	"PartitionAllocUnretainedDanglingPtr",
	FEATURE_ENABLED_BY_DEFAULT);

	constexpr FeatureParam<UnretainedDanglingPtrMode>::Option
	kUnretainedDanglingPtrModeOption[] = {
	{UnretainedDanglingPtrMode::kCrash, "crash"},
	{UnretainedDanglingPtrMode::kDumpWithoutCrashing,
	"dump_without_crashing"},
	};
	const base::FeatureParam<UnretainedDanglingPtrMode>
	kUnretainedDanglingPtrModeParam = {
	&kPartitionAllocUnretainedDanglingPtr,
	"mode",
	UnretainedDanglingPtrMode::kDumpWithoutCrashing,
	&kUnretainedDanglingPtrModeOption,
	};

	BASE_FEATURE(kPartitionAllocDanglingPtr,
	"PartitionAllocDanglingPtr",
	#if BUILDFLAG(ENABLE_DANGLING_RAW_PTR_FEATURE_FLAG) \|\| \
	(BUILDFLAG(ENABLE_DANGLING_RAW_PTR_CHECKS) && BUILDFLAG(IS_LINUX) && \
	!defined(OFFICIAL_BUILD) && (!defined(NDEBUG) \|\| DCHECK_IS_ON()))
	FEATURE_ENABLED_BY_DEFAULT
	#else
	FEATURE_DISABLED_BY_DEFAULT
	#endif
	);

	constexpr FeatureParam<DanglingPtrMode>::Option kDanglingPtrModeOption[] = {
	{DanglingPtrMode::kCrash, "crash"},
	{DanglingPtrMode::kLogOnly, "log_only"},
	};
	const base::FeatureParam<DanglingPtrMode> kDanglingPtrModeParam{
	&kPartitionAllocDanglingPtr,
	"mode",
	DanglingPtrMode::kCrash,
	&kDanglingPtrModeOption,
	};
	constexpr FeatureParam<DanglingPtrType>::Option kDanglingPtrTypeOption[] = {
	{DanglingPtrType::kAll, "all"},
	{DanglingPtrType::kCrossTask, "cross_task"},
	};
	const base::FeatureParam<DanglingPtrType> kDanglingPtrTypeParam{
	&kPartitionAllocDanglingPtr,
	"type",
	DanglingPtrType::kAll,
	&kDanglingPtrTypeOption,
	};

	#if BUILDFLAG(USE_STARSCAN)
	// If enabled, PCScan is turned on by default for all partitions that don't
	// disable it explicitly.
	BASE_FEATURE(kPartitionAllocPCScan,
	"PartitionAllocPCScan",
	FEATURE_DISABLED_BY_DEFAULT);
	#endif // BUILDFLAG(USE_STARSCAN)

	#if BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
	// If enabled, PCScan is turned on only for the browser's malloc partition.
	BASE_FEATURE(kPartitionAllocPCScanBrowserOnly,
	"PartitionAllocPCScanBrowserOnly",
	FEATURE_DISABLED_BY_DEFAULT);

	// If enabled, PCScan is turned on only for the renderer's malloc partition.
	BASE_FEATURE(kPartitionAllocPCScanRendererOnly,
	"PartitionAllocPCScanRendererOnly",
	FEATURE_DISABLED_BY_DEFAULT);

	// Use a larger maximum thread cache cacheable bucket size.
	BASE_FEATURE(kPartitionAllocLargeThreadCacheSize,
	"PartitionAllocLargeThreadCacheSize",
	FEATURE_ENABLED_BY_DEFAULT);

	MIRACLE_PARAMETER_FOR_INT(
	GetPartitionAllocLargeThreadCacheSizeValue,
	kPartitionAllocLargeThreadCacheSize,
	"PartitionAllocLargeThreadCacheSizeValue",
	::partition_alloc::ThreadCacheLimits::kLargeSizeThreshold)

	MIRACLE_PARAMETER_FOR_INT(
	GetPartitionAllocLargeThreadCacheSizeValueForLowRAMAndroid,
	kPartitionAllocLargeThreadCacheSize,
	"PartitionAllocLargeThreadCacheSizeValueForLowRAMAndroid",
	::partition_alloc::ThreadCacheLimits::kDefaultSizeThreshold)

	BASE_FEATURE(kPartitionAllocLargeEmptySlotSpanRing,
	"PartitionAllocLargeEmptySlotSpanRing",
	FEATURE_DISABLED_BY_DEFAULT);

	BASE_FEATURE(kPartitionAllocSchedulerLoopQuarantine,
	"PartitionAllocSchedulerLoopQuarantine",
	FEATURE_DISABLED_BY_DEFAULT);
	// Scheduler Loop Quarantine's capacity in bytes.
	const base::FeatureParam<int> kPartitionAllocSchedulerLoopQuarantineCapacity{
	&kPartitionAllocSchedulerLoopQuarantine,
	"PartitionAllocSchedulerLoopQuarantineCapacity", 0};

	BASE_FEATURE(kPartitionAllocZappingByFreeFlags,
	"PartitionAllocZappingByFreeFlags",
	FEATURE_DISABLED_BY_DEFAULT);
	#endif // BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)

	BASE_FEATURE(kPartitionAllocBackupRefPtr,
	"PartitionAllocBackupRefPtr",
	#if BUILDFLAG(IS_ANDROID) \|\| BUILDFLAG(IS_WIN) \|\| BUILDFLAG(IS_MAC) \|\| \
	BUILDFLAG(IS_CHROMEOS_ASH) \|\| BUILDFLAG(IS_CHROMEOS_LACROS) \|\| \
	(BUILDFLAG(IS_LINUX) && !BUILDFLAG(IS_CASTOS)) \|\| \
	BUILDFLAG(ENABLE_BACKUP_REF_PTR_FEATURE_FLAG)
	FEATURE_ENABLED_BY_DEFAULT
	#else
	FEATURE_DISABLED_BY_DEFAULT
	#endif
	);

	BASE_EXPORT BASE_DECLARE_FEATURE(kPartitionAllocBackupRefPtrForAsh);
	BASE_FEATURE(kPartitionAllocBackupRefPtrForAsh,
	"PartitionAllocBackupRefPtrForAsh",
	FEATURE_ENABLED_BY_DEFAULT);

	constexpr FeatureParam<BackupRefPtrEnabledProcesses>::Option
	kBackupRefPtrEnabledProcessesOptions[] = {
	{BackupRefPtrEnabledProcesses::kBrowserOnly, "browser-only"},
	{BackupRefPtrEnabledProcesses::kBrowserAndRenderer,
	"browser-and-renderer"},
	{BackupRefPtrEnabledProcesses::kNonRenderer, "non-renderer"},
	{BackupRefPtrEnabledProcesses::kAllProcesses, "all-processes"}};

	const base::FeatureParam<BackupRefPtrEnabledProcesses>
	kBackupRefPtrEnabledProcessesParam{
	&kPartitionAllocBackupRefPtr, "enabled-processes",
	BackupRefPtrEnabledProcesses::kNonRenderer,
	&kBackupRefPtrEnabledProcessesOptions};

	constexpr FeatureParam<BackupRefPtrRefCountSize>::Option
	kBackupRefPtrRefCountSizeOptions[] = {
	{BackupRefPtrRefCountSize::kNatural, "natural"},
	{BackupRefPtrRefCountSize::k4B, "4B"},
	{BackupRefPtrRefCountSize::k8B, "8B"},
	{BackupRefPtrRefCountSize::k16B, "16B"}};

	const base::FeatureParam<BackupRefPtrRefCountSize>
	kBackupRefPtrRefCountSizeParam{
	&kPartitionAllocBackupRefPtr, "ref-count-size",
	BackupRefPtrRefCountSize::kNatural, &kBackupRefPtrRefCountSizeOptions};

	// Map -with-memory-reclaimer modes onto their counterpars without the suffix.
	// They are the same, as memory reclaimer is now controlled independently.
	// However, we need to keep both option strings, as there is a long tail of
	// clients that may have an old field trial config, which used these modes.
	//
	// DO NOT USE -with-memory-reclaimer modes in new configs!
	constexpr FeatureParam<BackupRefPtrMode>::Option kBackupRefPtrModeOptions[] = {
	{BackupRefPtrMode::kDisabled, "disabled"},
	{BackupRefPtrMode::kEnabled, "enabled"},
	{BackupRefPtrMode::kEnabled, "enabled-with-memory-reclaimer"},
	{BackupRefPtrMode::kDisabledButSplitPartitions2Way,
	"disabled-but-2-way-split"},
	{BackupRefPtrMode::kDisabledButSplitPartitions2Way,
	"disabled-but-2-way-split-with-memory-reclaimer"},
	{BackupRefPtrMode::kDisabledButSplitPartitions3Way,
	"disabled-but-3-way-split"},
	};

	const base::FeatureParam<BackupRefPtrMode> kBackupRefPtrModeParam{
	&kPartitionAllocBackupRefPtr, "brp-mode", BackupRefPtrMode::kEnabled,
	&kBackupRefPtrModeOptions};

	BASE_FEATURE(kPartitionAllocMemoryTagging,
	"PartitionAllocMemoryTagging",
	FEATURE_DISABLED_BY_DEFAULT);

	constexpr FeatureParam<MemtagMode>::Option kMemtagModeOptions[] = {
	{MemtagMode::kSync, "sync"},
	{MemtagMode::kAsync, "async"}};

	const base::FeatureParam<MemtagMode> kMemtagModeParam{
	&kPartitionAllocMemoryTagging, "memtag-mode", MemtagMode::kAsync,
	&kMemtagModeOptions};

	constexpr FeatureParam<MemoryTaggingEnabledProcesses>::Option
	kMemoryTaggingEnabledProcessesOptions[] = {
	{MemoryTaggingEnabledProcesses::kBrowserOnly, "browser-only"},
	{MemoryTaggingEnabledProcesses::kNonRenderer, "non-renderer"},
	{MemoryTaggingEnabledProcesses::kAllProcesses, "all-processes"}};

	const base::FeatureParam<MemoryTaggingEnabledProcesses>
	kMemoryTaggingEnabledProcessesParam{
	&kPartitionAllocMemoryTagging, "enabled-processes",
	MemoryTaggingEnabledProcesses::kBrowserOnly,
	&kMemoryTaggingEnabledProcessesOptions};

	BASE_FEATURE(kKillPartitionAllocMemoryTagging,
	"KillPartitionAllocMemoryTagging",
	FEATURE_DISABLED_BY_DEFAULT);

	BASE_EXPORT BASE_DECLARE_FEATURE(kPartitionAllocPermissiveMte);
	BASE_FEATURE(kPartitionAllocPermissiveMte,
	"PartitionAllocPermissiveMte",
	FEATURE_ENABLED_BY_DEFAULT);

	const base::FeatureParam<bool> kBackupRefPtrAsanEnableDereferenceCheckParam{
	&kPartitionAllocBackupRefPtr, "asan-enable-dereference-check", true};
	const base::FeatureParam<bool> kBackupRefPtrAsanEnableExtractionCheckParam{
	&kPartitionAllocBackupRefPtr, "asan-enable-extraction-check",
	false}; // Not much noise at the moment to enable by default.
	const base::FeatureParam<bool> kBackupRefPtrAsanEnableInstantiationCheckParam{
	&kPartitionAllocBackupRefPtr, "asan-enable-instantiation-check", true};

	// If enabled, switches the bucket distribution to a denser one.
	//
	// We enable this by default everywhere except for 32-bit Android, since we saw
	// regressions there.
	BASE_FEATURE(kPartitionAllocUseDenserDistribution,
	"PartitionAllocUseDenserDistribution",
	#if BUILDFLAG(IS_ANDROID) && defined(ARCH_CPU_32_BITS)
	FEATURE_DISABLED_BY_DEFAULT
	#else
	FEATURE_ENABLED_BY_DEFAULT
	#endif // BUILDFLAG(IS_ANDROID) && defined(ARCH_CPU_32_BITS)
	);
	const base::FeatureParam<BucketDistributionMode>::Option
	kPartitionAllocBucketDistributionOption[] = {
	{BucketDistributionMode::kDefault, "default"},
	{BucketDistributionMode::kDenser, "denser"},
	};
	const base::FeatureParam<BucketDistributionMode>
	kPartitionAllocBucketDistributionParam {
	&kPartitionAllocUseDenserDistribution, "mode",
	#if BUILDFLAG(IS_ANDROID) && defined(ARCH_CPU_32_BITS)
	BucketDistributionMode::kDefault,
	#else
	BucketDistributionMode::kDenser,
	#endif // BUILDFLAG(IS_ANDROID) && defined(ARCH_CPU_32_BITS)
	&kPartitionAllocBucketDistributionOption
	};

	BASE_FEATURE(kPartitionAllocMemoryReclaimer,
	"PartitionAllocMemoryReclaimer",
	FEATURE_ENABLED_BY_DEFAULT);
	const base::FeatureParam<TimeDelta> kPartitionAllocMemoryReclaimerInterval = {
	&kPartitionAllocMemoryReclaimer, "interval",
	TimeDelta(), // Defaults to zero.
	};

	// Configures whether we set a lower limit for renderers that do not have a main
	// frame, similar to the limit that is already done for backgrounded renderers.
	BASE_FEATURE(kLowerPAMemoryLimitForNonMainRenderers,
	"LowerPAMemoryLimitForNonMainRenderers",
	FEATURE_DISABLED_BY_DEFAULT);

	// If enabled, switches PCScan scheduling to a mutator-aware scheduler. Does not
	// affect whether PCScan is enabled itself.
	BASE_FEATURE(kPartitionAllocPCScanMUAwareScheduler,
	"PartitionAllocPCScanMUAwareScheduler",
	FEATURE_ENABLED_BY_DEFAULT);

	// If enabled, PCScan frees unconditionally all quarantined objects.
	// This is a performance testing feature.
	BASE_FEATURE(kPartitionAllocPCScanImmediateFreeing,
	"PartitionAllocPCScanImmediateFreeing",
	FEATURE_DISABLED_BY_DEFAULT);

	// If enabled, PCScan clears eagerly (synchronously) on free().
	BASE_FEATURE(kPartitionAllocPCScanEagerClearing,
	"PartitionAllocPCScanEagerClearing",
	FEATURE_DISABLED_BY_DEFAULT);

	// In addition to heap, scan also the stack of the current mutator.
	BASE_FEATURE(kPartitionAllocPCScanStackScanning,
	"PartitionAllocPCScanStackScanning",
	#if BUILDFLAG(PCSCAN_STACK_SUPPORTED)
	FEATURE_ENABLED_BY_DEFAULT
	#else
	FEATURE_DISABLED_BY_DEFAULT
	#endif // BUILDFLAG(PCSCAN_STACK_SUPPORTED)
	);

	BASE_FEATURE(kPartitionAllocDCScan,
	"PartitionAllocDCScan",
	FEATURE_DISABLED_BY_DEFAULT);

	// Whether to straighten free lists for larger slot spans in PurgeMemory() ->
	// ... -> PartitionPurgeSlotSpan().
	BASE_FEATURE(kPartitionAllocStraightenLargerSlotSpanFreeLists,
	"PartitionAllocStraightenLargerSlotSpanFreeLists",
	FEATURE_ENABLED_BY_DEFAULT);
	const base::FeatureParam<
	partition_alloc::StraightenLargerSlotSpanFreeListsMode>::Option
	kPartitionAllocStraightenLargerSlotSpanFreeListsModeOption[] = {
	{partition_alloc::StraightenLargerSlotSpanFreeListsMode::
	kOnlyWhenUnprovisioning,
	"only-when-unprovisioning"},
	{partition_alloc::StraightenLargerSlotSpanFreeListsMode::kAlways,
	"always"},
	};
	const base::FeatureParam<partition_alloc::StraightenLargerSlotSpanFreeListsMode>
	kPartitionAllocStraightenLargerSlotSpanFreeListsMode = {
	&kPartitionAllocStraightenLargerSlotSpanFreeLists,
	"mode",
	partition_alloc::StraightenLargerSlotSpanFreeListsMode::
	kOnlyWhenUnprovisioning,
	&kPartitionAllocStraightenLargerSlotSpanFreeListsModeOption,
	};

	// Whether to sort free lists for smaller slot spans in PurgeMemory().
	BASE_FEATURE(kPartitionAllocSortSmallerSlotSpanFreeLists,
	"PartitionAllocSortSmallerSlotSpanFreeLists",
	FEATURE_ENABLED_BY_DEFAULT);

	// Whether to sort the active slot spans in PurgeMemory().
	BASE_FEATURE(kPartitionAllocSortActiveSlotSpans,
	"PartitionAllocSortActiveSlotSpans",
	FEATURE_DISABLED_BY_DEFAULT);

	#if BUILDFLAG(IS_WIN)
	// Whether to retry allocations when commit fails.
	BASE_FEATURE(kPageAllocatorRetryOnCommitFailure,
	"PageAllocatorRetryOnCommitFailure",
	FEATURE_DISABLED_BY_DEFAULT);
	#endif

	#if BUILDFLAG(IS_ANDROID) \|\| BUILDFLAG(IS_CHROMEOS)
	// A parameter to exclude or not exclude PartitionAllocSupport from
	// PartialLowModeOnMidRangeDevices. This is used to see how it affects
	// renderer performances, e.g. blink_perf.parser benchmark.
	// The feature: kPartialLowEndModeOnMidRangeDevices is defined in
	// //base/features.cc. Since the following feature param is related to
	// PartitionAlloc, define the param here.
	const FeatureParam<bool> kPartialLowEndModeExcludePartitionAllocSupport{
	&kPartialLowEndModeOnMidRangeDevices, "exclude-partition-alloc-support",
	false};
	#endif

	BASE_FEATURE(kEnableConfigurableThreadCacheMultiplier,
	"EnableConfigurableThreadCacheMultiplier",
	base::FEATURE_DISABLED_BY_DEFAULT);

	MIRACLE_PARAMETER_FOR_DOUBLE(GetThreadCacheMultiplier,
	kEnableConfigurableThreadCacheMultiplier,
	"ThreadCacheMultiplier",
	2.)

	MIRACLE_PARAMETER_FOR_DOUBLE(GetThreadCacheMultiplierForAndroid,
	kEnableConfigurableThreadCacheMultiplier,
	"ThreadCacheMultiplierForAndroid",
	1.)

	constexpr partition_alloc::internal::base::TimeDelta ToPartitionAllocTimeDelta(
	base::TimeDelta time_delta) {
	return partition_alloc::internal::base::Microseconds(
	time_delta.InMicroseconds());
	}

	constexpr base::TimeDelta FromPartitionAllocTimeDelta(
	partition_alloc::internal::base::TimeDelta time_delta) {
	return base::Microseconds(time_delta.InMicroseconds());
	}

	BASE_FEATURE(kEnableConfigurableThreadCachePurgeInterval,
	"EnableConfigurableThreadCachePurgeInterval",
	base::FEATURE_DISABLED_BY_DEFAULT);

	MIRACLE_PARAMETER_FOR_TIME_DELTA(
	GetThreadCacheMinPurgeIntervalValue,
	kEnableConfigurableThreadCachePurgeInterval,
	"ThreadCacheMinPurgeInterval",
	FromPartitionAllocTimeDelta(partition_alloc::kMinPurgeInterval))

	MIRACLE_PARAMETER_FOR_TIME_DELTA(
	GetThreadCacheMaxPurgeIntervalValue,
	kEnableConfigurableThreadCachePurgeInterval,
	"ThreadCacheMaxPurgeInterval",
	FromPartitionAllocTimeDelta(partition_alloc::kMaxPurgeInterval))

	MIRACLE_PARAMETER_FOR_TIME_DELTA(
	GetThreadCacheDefaultPurgeIntervalValue,
	kEnableConfigurableThreadCachePurgeInterval,
	"ThreadCacheDefaultPurgeInterval",
	FromPartitionAllocTimeDelta(partition_alloc::kDefaultPurgeInterval))

	const partition_alloc::internal::base::TimeDelta
	GetThreadCacheMinPurgeInterval() {
	return ToPartitionAllocTimeDelta(GetThreadCacheMinPurgeIntervalValue());
	}

	const partition_alloc::internal::base::TimeDelta
	GetThreadCacheMaxPurgeInterval() {
	return ToPartitionAllocTimeDelta(GetThreadCacheMaxPurgeIntervalValue());
	}

	const partition_alloc::internal::base::TimeDelta
	GetThreadCacheDefaultPurgeInterval() {
	return ToPartitionAllocTimeDelta(GetThreadCacheDefaultPurgeIntervalValue());
	}

	BASE_FEATURE(kEnableConfigurableThreadCacheMinCachedMemoryForPurging,
	"EnableConfigurableThreadCacheMinCachedMemoryForPurging",
	base::FEATURE_DISABLED_BY_DEFAULT);

	MIRACLE_PARAMETER_FOR_INT(
	GetThreadCacheMinCachedMemoryForPurgingBytes,
	kEnableConfigurableThreadCacheMinCachedMemoryForPurging,
	"ThreadCacheMinCachedMemoryForPurgingBytes",
	partition_alloc::kMinCachedMemoryForPurgingBytes)

	// An apparent quarantine leak in the buffer partition unacceptably
	// bloats memory when MiraclePtr is enabled in the renderer process.
	// We believe we have found and patched the leak, but out of an
	// abundance of caution, we provide this toggle that allows us to
	// wholly disable MiraclePtr in the buffer partition, if necessary.
	//
	// TODO(crbug.com/1444624): this is unneeded once
	// MiraclePtr-for-Renderer launches.
	BASE_FEATURE(kPartitionAllocDisableBRPInBufferPartition,
	"PartitionAllocDisableBRPInBufferPartition",
	FEATURE_DISABLED_BY_DEFAULT);

	#if BUILDFLAG(USE_FREELIST_POOL_OFFSETS)
	BASE_FEATURE(kUsePoolOffsetFreelists,
	"PartitionAllocUsePoolOffsetFreelists",
	base::FEATURE_DISABLED_BY_DEFAULT);
	#endif

	} // namespace features
	} // namespace base