[scudo][standalone] Allow setting release to OS

[cferris]

Summary

Add a method to set the release to OS value as the system runs,
and allow this to be set differently in the primary and the secondary.
Also, add a default value to use for primary and secondary. This
allows Android to have a default that is different for
primary/secondary.

Update mallopt to support setting the release to OS value.

[cferris]

I added a parameter to the primary and secondary, but I'm not sure when to set using the default. Right now, if the flag release_to_os_interval is set to -1, then it uses the default. I think that it would be better to have the default always override, but what do you think?

[cryptoad]

I think this works.
Once the comment raised is addressed, this can go in like this, and my next step would be to change the parameters to a Config class like it's done in other places and like pcc@ did for the new sizeclassmap.

compiler-rt/lib/scudo/standalone/primary64.h

98

With this block, I don't think we can ever set a negative interval (eg: never release) via the options string if the default is not negative.
A possible solution could be to have a specific "not-specified" value for the parameter default maybe that would entice a fallback to the default value (an enum/define of INT32_MAX maybe or something negative)?

[cferris]

• Merge branch 'master' of https://github.com/llvm/llvm-project

[cferris]

Created a min and max release to OS value for the allocators.

[cryptoad]

Running some tests, 1 comment.

compiler-rt/lib/scudo/standalone/wrappers_c.inc

165

Now that value & secondary_interval have the same values, does it make sense to merge them?

[cryptoad]

compiler-rt/lib/scudo/standalone/combined.h

631

error: conversion from ‘scudo::sptr’ {aka ‘long int’} to ‘scudo::s32’ {aka ‘int’} may change value [-Werror=conversion]
so static_cast to s32.

634

Same here

[cferris]

Add static_casts where needed.

[cferris]

Update the mallopt and remove the ability to set the
primary and secondary differently.

[cferris]

compiler-rt/lib/scudo/standalone/wrappers_c.inc

165

Good point, I've removed the ability to set the two differently since it's not needed now, and I'm not sure if it's something we'll want in the future.

compiler-rt/lib/scudo/standalone/allocator_config.h

#endif
   typedef MapAllocator<MapAllocatorCache<>> Secondary;
   template <class A> using TSDRegistryT = TSDRegistryExT<A>; // Exclusive
 };
 
 struct AndroidConfig {
   using SizeClassMap = AndroidSizeClassMap;
 #if SCUDO_CAN_USE_PRIMARY64
   // 256MB regions
-  typedef SizeClassAllocator64<SizeClassMap, 28U,
+  typedef SizeClassAllocator64<SizeClassMap, 28U, 1000, 1000,
                                /*MaySupportMemoryTagging=*/true>
       Primary;
 #else
   // 256KB regions
-  typedef SizeClassAllocator32<SizeClassMap, 18U> Primary;
+  typedef SizeClassAllocator32<SizeClassMap, 18U, 1000, 1000> Primary;
 #endif
   // Cache blocks up to 2MB
-  typedef MapAllocator<MapAllocatorCache<32U, 2UL << 20>> Secondary;
+  typedef MapAllocator<MapAllocatorCache<32U, 2UL << 20, 0, 1000>> Secondary;
   template <class A>
   using TSDRegistryT = TSDRegistrySharedT<A, 2U>; // Shared, max 2 TSDs.
 };
 
 struct AndroidSvelteConfig {
   using SizeClassMap = SvelteSizeClassMap;
 #if SCUDO_CAN_USE_PRIMARY64
   // 128MB regions
-  typedef SizeClassAllocator64<SizeClassMap, 27U> Primary;
+  typedef SizeClassAllocator64<SizeClassMap, 27U, 1000, 1000> Primary;
 #else
   // 64KB regions
-  typedef SizeClassAllocator32<SizeClassMap, 16U> Primary;
+  typedef SizeClassAllocator32<SizeClassMap, 16U, 1000, 1000> Primary;
 #endif
-  typedef MapAllocator<MapAllocatorCache<4U, 1UL << 18>> Secondary;
+  typedef MapAllocator<MapAllocatorCache<4U, 1UL << 18, 0, 0>> Secondary;
   template <class A>
   using TSDRegistryT = TSDRegistrySharedT<A, 1U>; // Shared, only 1 TSD.
 };
 
 #if SCUDO_CAN_USE_PRIMARY64
 struct FuchsiaConfig {
   // 1GB Regions
   typedef SizeClassAllocator64<DefaultSizeClassMap, 30U> Primary;

compiler-rt/lib/scudo/standalone/combined.h

 #include "gwp_asan/optional/backtrace.h"
 #include "gwp_asan/optional/segv_handler.h"
 #endif // GWP_ASAN_HOOKS
 
 extern "C" inline void EmptyCallback() {}
 
 namespace scudo {
 
+enum class Option { ReleaseInterval };
+
 template <class Params, void (*PostInitCallback)(void) = EmptyCallback>
 class Allocator {
 public:
   using PrimaryT = typename Params::Primary;
   using CacheT = typename PrimaryT::CacheT;
   typedef Allocator<Params, PostInitCallback> ThisT;
   typedef typename Params::template TSDRegistryT<ThisT> TSDRegistryT;
 

 #endif
   }
 
   bool canReturnNull() {
     initThreadMaybe();
     return Options.MayReturnNull;
   }
 
-  // TODO(kostyak): implement this as a "backend" to mallopt.
-  bool setOption(UNUSED uptr Option, UNUSED uptr Value) { return false; }
+  bool setOption(Option O, sptr Value) {
+    if (O == Option::ReleaseInterval) {
+      Primary.setReleaseToOsIntervalMs(static_cast<s32>(Value));
+      Secondary.setReleaseToOsIntervalMs(static_cast<s32>(Value));
+      return true;
+    }
+    return false;
+  }
 
   // Return the usable size for a given chunk. Technically we lie, as we just
   // report the actual size of a chunk. This is done to counteract code actively
   // writing past the end of a chunk (like sqlite3) when the usable size allows
   // for it, which then forces realloc to copy the usable size of a chunk as
   // opposed to its actual size.
   uptr getUsableSize(const void *Ptr) {
     initThreadMaybe();

compiler-rt/lib/scudo/standalone/flags.inc

SCUDO_FLAG(int, rss_limit_mb, -1,
            "attempted past that limit (depending on may_return_null). Negative "
            "values disable the feature.")
 
 SCUDO_FLAG(bool, may_return_null, true,
            "Indicate whether the allocator should terminate instead of "
            "returning NULL in otherwise non-fatal error scenarios, eg: OOM, "
            "invalid allocation alignments, etc.")
 
-SCUDO_FLAG(int, release_to_os_interval_ms, SCUDO_ANDROID ? 1000 : 5000,
+SCUDO_FLAG(int, release_to_os_interval_ms, SCUDO_ANDROID ? INT32_MIN : 5000,
            "Interval (in milliseconds) at which to attempt release of unused "
            "memory to the OS. Negative values disable the feature.")

compiler-rt/lib/scudo/standalone/primary32.h

 //
 // Regions for size class 0 are special and used to hold TransferBatches, which
 // allow to transfer arrays of pointers from the global size class freelist to
 // the thread specific freelist for said class, and back.
 //
 // Memory used by this allocator is never unmapped but can be partially
 // reclaimed if the platform allows for it.
 
-template <class SizeClassMapT, uptr RegionSizeLog> class SizeClassAllocator32 {
+template <class SizeClassMapT, uptr RegionSizeLog,
+          s32 MinReleaseToOsIntervalMs = INT32_MIN,
+          s32 MaxReleaseToOsIntervalMs = INT32_MAX> class SizeClassAllocator32 {
 public:
   typedef SizeClassMapT SizeClassMap;
   // The bytemap can only track UINT8_MAX - 1 classes.
   static_assert(SizeClassMap::LargestClassId <= (UINT8_MAX - 1), "");
   // Regions should be large enough to hold the largest Block.
   static_assert((1UL << RegionSizeLog) >= SizeClassMap::MaxSize, "");
-  typedef SizeClassAllocator32<SizeClassMapT, RegionSizeLog> ThisT;
+  typedef SizeClassAllocator32<SizeClassMapT, RegionSizeLog,
+                               MinReleaseToOsIntervalMs,
+                               MaxReleaseToOsIntervalMs> ThisT;
   typedef SizeClassAllocatorLocalCache<ThisT> CacheT;
   typedef typename CacheT::TransferBatch TransferBatch;
   static const bool SupportsMemoryTagging = false;
 
   static uptr getSizeByClassId(uptr ClassId) {
     return (ClassId == SizeClassMap::BatchClassId)
                ? sizeof(TransferBatch)
                : SizeClassMap::getSizeByClassId(ClassId);
void initLinkerInitialized(s32 ReleaseToOsInterval) {
     const uptr PageSize = getPageSizeCached();
     for (uptr I = 0; I < NumClasses; I++) {
       SizeClassInfo *Sci = getSizeClassInfo(I);
       Sci->RandState = getRandomU32(&Seed);
       // See comment in the 64-bit primary about releasing smaller size classes.
       Sci->CanRelease = (I != SizeClassMap::BatchClassId) &&
                         (getSizeByClassId(I) >= (PageSize / 32));
     }
-    ReleaseToOsIntervalMs = ReleaseToOsInterval;
+    setReleaseToOsIntervalMs(ReleaseToOsInterval);
   }
   void init(s32 ReleaseToOsInterval) {
     memset(this, 0, sizeof(*this));
     initLinkerInitialized(ReleaseToOsInterval);
   }
 
   void unmapTestOnly() {
     while (NumberOfStashedRegions > 0)
void getStats(ScopedString *Str) {
     }
     Str->append("Stats: SizeClassAllocator32: %zuM mapped in %zu allocations; "
                 "remains %zu\n",
                 TotalMapped >> 20, PoppedBlocks, PoppedBlocks - PushedBlocks);
     for (uptr I = 0; I < NumClasses; I++)
       getStats(Str, I, 0);
   }
 
+  void setReleaseToOsIntervalMs(s32 Interval) {
+    if (Interval >= MaxReleaseToOsIntervalMs) {
+      Interval = MaxReleaseToOsIntervalMs;
+    } else if (Interval <= MinReleaseToOsIntervalMs) {
+      Interval = MinReleaseToOsIntervalMs;
+    }
+    atomic_store(&ReleaseToOsIntervalMs, Interval, memory_order_relaxed);
+  }
+
   uptr releaseToOS() {
     uptr TotalReleasedBytes = 0;
     for (uptr I = 0; I < NumClasses; I++) {
       SizeClassInfo *Sci = getSizeClassInfo(I);
       ScopedLock L(Sci->Mutex);
       TotalReleasedBytes += releaseToOSMaybe(Sci, I, /*Force=*/true);
     }
     return TotalReleasedBytes;
void getStats(ScopedString *Str, uptr ClassId, uptr Rss) {
     const uptr AvailableChunks = Sci->AllocatedUser / getSizeByClassId(ClassId);
     Str->append("  %02zu (%6zu): mapped: %6zuK popped: %7zu pushed: %7zu "
                 "inuse: %6zu avail: %6zu rss: %6zuK releases: %6zu\n",
                 ClassId, getSizeByClassId(ClassId), Sci->AllocatedUser >> 10,
                 Sci->Stats.PoppedBlocks, Sci->Stats.PushedBlocks, InUse,
                 AvailableChunks, Rss >> 10, Sci->ReleaseInfo.RangesReleased);
   }
 
+  s32 getReleaseToOsIntervalMs() {
+    return atomic_load(&ReleaseToOsIntervalMs, memory_order_relaxed);
+  }
+
   NOINLINE uptr releaseToOSMaybe(SizeClassInfo *Sci, uptr ClassId,
                                  bool Force = false) {
     const uptr BlockSize = getSizeByClassId(ClassId);
     const uptr PageSize = getPageSizeCached();
 
     CHECK_GE(Sci->Stats.PoppedBlocks, Sci->Stats.PushedBlocks);
     const uptr BytesInFreeList =
         Sci->AllocatedUser -
         (Sci->Stats.PoppedBlocks - Sci->Stats.PushedBlocks) * BlockSize;
     if (BytesInFreeList < PageSize)
       return 0; // No chance to release anything.
     if ((Sci->Stats.PushedBlocks - Sci->ReleaseInfo.PushedBlocksAtLastRelease) *
             BlockSize <
         PageSize) {
       return 0; // Nothing new to release.
     }
 
     if (!Force) {
-      const s32 IntervalMs = ReleaseToOsIntervalMs;
+      const s32 IntervalMs = getReleaseToOsIntervalMs();
       if (IntervalMs < 0)
         return 0;
       if (Sci->ReleaseInfo.LastReleaseAtNs +
               static_cast<u64>(IntervalMs) * 1000000 >
           getMonotonicTime()) {
         return 0; // Memory was returned recently.
       }
     }
private:
   SizeClassInfo SizeClassInfoArray[NumClasses];
 
   // Track the regions in use, 0 is unused, otherwise store ClassId + 1.
   ByteMap PossibleRegions;
   // Keep track of the lowest & highest regions allocated to avoid looping
   // through the whole NumRegions.
   uptr MinRegionIndex;
   uptr MaxRegionIndex;
-  s32 ReleaseToOsIntervalMs;
+  atomic_s32 ReleaseToOsIntervalMs;
   // Unless several threads request regions simultaneously from different size
   // classes, the stash rarely contains more than 1 entry.
   static constexpr uptr MaxStashedRegions = 4;
   HybridMutex RegionsStashMutex;
   uptr NumberOfStashedRegions;
   uptr RegionsStash[MaxStashedRegions];
 };
 
 } // namespace scudo
 
 #endif // SCUDO_PRIMARY32_H_

compiler-rt/lib/scudo/standalone/primary64.h

 // The 1st Region (for size class 0) holds the TransferBatches. This is a
 // structure used to transfer arrays of available pointers from the class size
 // freelist to the thread specific freelist, and back.
 //
 // The memory used by this allocator is never unmapped, but can be partially
 // released if the platform allows for it.
 
 template <class SizeClassMapT, uptr RegionSizeLog,
+          s32 MinReleaseToOsIntervalMs = INT32_MIN,
+          s32 MaxReleaseToOsIntervalMs = INT32_MAX,
           bool MaySupportMemoryTagging = false>
 class SizeClassAllocator64 {
 public:
   typedef SizeClassMapT SizeClassMap;
   typedef SizeClassAllocator64<SizeClassMap, RegionSizeLog,
+                               MinReleaseToOsIntervalMs,
+                               MaxReleaseToOsIntervalMs,
                                MaySupportMemoryTagging>
       ThisT;
   typedef SizeClassAllocatorLocalCache<ThisT> CacheT;
   typedef typename CacheT::TransferBatch TransferBatch;
   static const bool SupportsMemoryTagging =
       MaySupportMemoryTagging && archSupportsMemoryTagging();
 
   static uptr getSizeByClassId(uptr ClassId) {
for (uptr I = 0; I < NumClasses; I++) {
       // On top of this, attempting to release those require more iterations and
       // memory accesses which ends up being fairly costly. The current lower
       // limit is mostly arbitrary and based on empirical observations.
       // TODO(kostyak): make the lower limit a runtime option
       Region->CanRelease = (I != SizeClassMap::BatchClassId) &&
                            (getSizeByClassId(I) >= (PageSize / 32));
       Region->RandState = getRandomU32(&Seed);
     }
-    ReleaseToOsIntervalMs = ReleaseToOsInterval;
+    setReleaseToOsIntervalMs(ReleaseToOsInterval);
 
     if (SupportsMemoryTagging)
       UseMemoryTagging = systemSupportsMemoryTagging();
   }
   void init(s32 ReleaseToOsInterval) {
     memset(this, 0, sizeof(*this));
     initLinkerInitialized(ReleaseToOsInterval);
   }
 
Str->append("Stats: SizeClassAllocator64: %zuM mapped (%zuM rss) in %zu "
                 "allocations; remains %zu\n",
                 TotalMapped >> 20, 0, PoppedBlocks,
                 PoppedBlocks - PushedBlocks);
 
     for (uptr I = 0; I < NumClasses; I++)
       getStats(Str, I, 0);
   }
 
+  void setReleaseToOsIntervalMs(s32 Interval) {
+    if (Interval >= MaxReleaseToOsIntervalMs) {
+      Interval = MaxReleaseToOsIntervalMs;
+    } else if (Interval <= MinReleaseToOsIntervalMs) {
+      Interval = MinReleaseToOsIntervalMs;
+    }
+    atomic_store(&ReleaseToOsIntervalMs, Interval, memory_order_relaxed);
+  }
+
   uptr releaseToOS() {
     uptr TotalReleasedBytes = 0;
     for (uptr I = 0; I < NumClasses; I++) {
       RegionInfo *Region = getRegionInfo(I);
       ScopedLock L(Region->Mutex);
       TotalReleasedBytes += releaseToOSMaybe(Region, I, /*Force=*/true);
     }
     return TotalReleasedBytes;
struct ALIGNED(SCUDO_CACHE_LINE_SIZE) RegionInfo {
     MapPlatformData Data;
     ReleaseToOsInfo ReleaseInfo;
   };
   static_assert(sizeof(RegionInfo) % SCUDO_CACHE_LINE_SIZE == 0, "");
 
   uptr PrimaryBase;
   RegionInfo *RegionInfoArray;
   MapPlatformData Data;
-  s32 ReleaseToOsIntervalMs;
+  atomic_s32 ReleaseToOsIntervalMs;
   bool UseMemoryTagging;
 
   RegionInfo *getRegionInfo(uptr ClassId) const {
     DCHECK_LT(ClassId, NumClasses);
     return &RegionInfoArray[ClassId];
   }
 
   uptr getRegionBaseByClassId(uptr ClassId) const {
Str->append("%s %02zu (%6zu): mapped: %6zuK popped: %7zu pushed: %7zu "
                 Region->Exhausted ? "F" : " ", ClassId,
                 getSizeByClassId(ClassId), Region->MappedUser >> 10,
                 Region->Stats.PoppedBlocks, Region->Stats.PushedBlocks, InUse,
                 TotalChunks, Rss >> 10, Region->ReleaseInfo.RangesReleased,
                 Region->ReleaseInfo.LastReleasedBytes >> 10, Region->RegionBeg,
                 getRegionBaseByClassId(ClassId));
   }
 
+  s32 getReleaseToOsIntervalMs() {
+    return atomic_load(&ReleaseToOsIntervalMs, memory_order_relaxed);
+  }
+
   NOINLINE uptr releaseToOSMaybe(RegionInfo *Region, uptr ClassId,
                                  bool Force = false) {
     const uptr BlockSize = getSizeByClassId(ClassId);
     const uptr PageSize = getPageSizeCached();
 
     CHECK_GE(Region->Stats.PoppedBlocks, Region->Stats.PushedBlocks);
     const uptr BytesInFreeList =
         Region->AllocatedUser -
         (Region->Stats.PoppedBlocks - Region->Stats.PushedBlocks) * BlockSize;
     if (BytesInFreeList < PageSize)
       return 0; // No chance to release anything.
     if ((Region->Stats.PushedBlocks -
          Region->ReleaseInfo.PushedBlocksAtLastRelease) *
             BlockSize <
         PageSize) {
       return 0; // Nothing new to release.
     }
 
     if (!Force) {
-      const s32 IntervalMs = ReleaseToOsIntervalMs;
+      const s32 IntervalMs = getReleaseToOsIntervalMs();
       if (IntervalMs < 0)
         return 0;
       if (Region->ReleaseInfo.LastReleaseAtNs +
               static_cast<u64>(IntervalMs) * 1000000 >
           getMonotonicTime()) {
         return 0; // Memory was returned recently.
       }
     }

compiler-rt/lib/scudo/standalone/secondary.h

public:
   }
   bool store(UNUSED LargeBlock::Header *H) { return false; }
   static bool canCache(UNUSED uptr Size) { return false; }
   void disable() {}
   void enable() {}
   void releaseToOS() {}
 };
 
-template <uptr MaxEntriesCount = 32U, uptr MaxEntrySize = 1UL << 19>
+template <uptr MaxEntriesCount = 32U, uptr MaxEntrySize = 1UL << 19,
+          s32 MinReleaseToOsIntervalMs = INT32_MIN,
+          s32 MaxReleaseToOsIntervalMs = INT32_MAX>
 class MapAllocatorCache {
 public:
   // Fuchsia doesn't allow releasing Secondary blocks yet. Note that 0 length
   // arrays are an extension for some compilers.
   // FIXME(kostyak): support (partially) the cache on Fuchsia.
   static_assert(!SCUDO_FUCHSIA || MaxEntriesCount == 0U, "");
 
   void initLinkerInitialized(s32 ReleaseToOsInterval) {
-    ReleaseToOsIntervalMs = ReleaseToOsInterval;
+    setReleaseToOsIntervalMs(ReleaseToOsInterval);
   }
   void init(s32 ReleaseToOsInterval) {
     memset(this, 0, sizeof(*this));
     initLinkerInitialized(ReleaseToOsInterval);
   }
 
   bool store(LargeBlock::Header *H) {
     bool EntryCached = false;
const u64 Time = getMonotonicTime();
           Entries[0].Data = H->Data;
           Entries[0].Time = Time;
           EntriesCount++;
           EntryCached = true;
           break;
         }
       }
     }
+    s32 Interval;
     if (EmptyCache)
       empty();
-    else if (ReleaseToOsIntervalMs >= 0)
-      releaseOlderThan(Time -
-                       static_cast<u64>(ReleaseToOsIntervalMs) * 1000000);
+    else if ((Interval = getReleaseToOsIntervalMs()) >= 0)
+      releaseOlderThan(Time - static_cast<u64>(Interval) * 1000000);
     return EntryCached;
   }
 
   bool retrieve(uptr Size, LargeBlock::Header **H) {
     const uptr PageSize = getPageSizeCached();
     ScopedLock L(Mutex);
     if (EntriesCount == 0)
       return false;
bool retrieve(uptr Size, LargeBlock::Header **H) {
     }
     return false;
   }
 
   static bool canCache(uptr Size) {
     return MaxEntriesCount != 0U && Size <= MaxEntrySize;
   }
 
+  void setReleaseToOsIntervalMs(s32 Interval) {
+    if (Interval >= MaxReleaseToOsIntervalMs) {
+      Interval = MaxReleaseToOsIntervalMs;
+    } else if (Interval <= MinReleaseToOsIntervalMs) {
+      Interval = MinReleaseToOsIntervalMs;
+    }
+    atomic_store(&ReleaseToOsIntervalMs, Interval, memory_order_relaxed);
+  }
+
   void releaseToOS() { releaseOlderThan(UINT64_MAX); }
 
   void disable() { Mutex.lock(); }
 
   void enable() { Mutex.unlock(); }
 
 private:
   void empty() {
for (uptr I = 0; I < MaxEntriesCount; I++) {
         continue;
       releasePagesToOS(Entries[I].Block, 0,
                        Entries[I].BlockEnd - Entries[I].Block,
                        &Entries[I].Data);
       Entries[I].Time = 0;
     }
   }
 
+  s32 getReleaseToOsIntervalMs() {
+    return atomic_load(&ReleaseToOsIntervalMs, memory_order_relaxed);
+  }
+
   struct CachedBlock {
     uptr Block;
     uptr BlockEnd;
     uptr MapBase;
     uptr MapSize;
     MapPlatformData Data;
     u64 Time;
   };
 
   HybridMutex Mutex;
   CachedBlock Entries[MaxEntriesCount];
   u32 EntriesCount;
   uptr LargestSize;
   u32 IsFullEvents;
-  s32 ReleaseToOsIntervalMs;
+  atomic_s32 ReleaseToOsIntervalMs;
 };
 
 template <class CacheT> class MapAllocator {
 public:
   void initLinkerInitialized(GlobalStats *S, s32 ReleaseToOsInterval = -1) {
     Cache.initLinkerInitialized(ReleaseToOsInterval);
     Stats.initLinkerInitialized();
     if (LIKELY(S))
public:
 
   template <typename F> void iterateOverBlocks(F Callback) const {
     for (const auto &H : InUseBlocks)
       Callback(reinterpret_cast<uptr>(&H) + LargeBlock::getHeaderSize());
   }
 
   static uptr canCache(uptr Size) { return CacheT::canCache(Size); }
 
+  void setReleaseToOsIntervalMs(s32 Interval) {
+    Cache.setReleaseToOsIntervalMs(Interval);
+  }
+
   void releaseToOS() { Cache.releaseToOS(); }
 
 private:
   CacheT Cache;
 
   HybridMutex Mutex;
   DoublyLinkedList<LargeBlock::Header> InUseBlocks;
   uptr AllocatedBytes;

compiler-rt/lib/scudo/standalone/wrappers_c.inc

 void SCUDO_PREFIX(malloc_postinit)() {
   SCUDO_ALLOCATOR.initGwpAsan();
   pthread_atfork(SCUDO_PREFIX(malloc_disable), SCUDO_PREFIX(malloc_enable),
                  SCUDO_PREFIX(malloc_enable));
 }
 
 INTERFACE WEAK int SCUDO_PREFIX(mallopt)(int param, UNUSED int value) {
   if (param == M_DECAY_TIME) {
-    // TODO(kostyak): set release_to_os_interval_ms accordingly.
+    if (SCUDO_ANDROID) {
+      if (value == 0) {
+        // Will set the release values to their minimum values.
+        value = INT32_MIN;
+      } else {
+        // Will set the release values to their maximum values.
+        value = INT32_MAX;
+      }
+    }
+
+    SCUDO_ALLOCATOR.setOption(scudo::Option::ReleaseInterval,
+                              static_cast<scudo::sptr>(value));
     return 1;
   } else if (param == M_PURGE) {
     SCUDO_ALLOCATOR.releaseToOS();
     return 1;
   }
   return 0;
 }