malloc: default to malloc

pkg/common/malloc/c_allocator.go

@@ -16,7 +16,10 @@
 
 package malloc
 
-import "unsafe"
+import (
+	"sync/atomic"
+	"unsafe"
+)
 
 /*
 #include <stdlib.h>
@@ -25,24 +28,39 @@ import "C"
 
 type CAllocator struct {
 	deallocatorPool *ClosureDeallocatorPool[cDeallocatorArgs, *cDeallocatorArgs]
+	bytesFree       atomic.Uint64
 }
 
 type cDeallocatorArgs struct {
-	ptr unsafe.Pointer
+	ptr  unsafe.Pointer
+	size uint64
 }
 
 func (cDeallocatorArgs) As(Trait) bool {
 	return false
 }
 
-func NewCAllocator() *CAllocator {
-	return &CAllocator{
+const (
+	cMallocReturnToOSThreshold = 64 * MB
+)
+
+func NewCAllocator() (ret *CAllocator) {
+	ret = &CAllocator{
 		deallocatorPool: NewClosureDeallocatorPool(
 			func(hints Hints, args *cDeallocatorArgs) {
 				C.free(args.ptr)
+
+				n := ret.bytesFree.Add(args.size)
+				if n > cMallocReturnToOSThreshold {
+					ret.bytesFree.Store(0)
+					// return memory to OS
+					returnMallocMemoryToOS()
+				}
+
 			},
 		),
 	}
+	return
 }
 
 var _ Allocator = new(CAllocator)
@@ -54,6 +72,7 @@ func (c *CAllocator) Allocate(size uint64, hints Hints) ([]byte, Deallocator, er
 	}
 	slice := unsafe.Slice((*byte)(ptr), size)
 	return slice, c.deallocatorPool.Get(cDeallocatorArgs{
-		ptr: ptr,
+		ptr:  ptr,
+		size: size,
 	}), nil
 }

pkg/common/malloc/c_allocator_darwin.go

@@ -0,0 +1,20 @@
+// Copyright 2024 Matrix Origin
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build cgo
+
+package malloc
+
+func returnMallocMemoryToOS() {
+}

pkg/common/malloc/c_allocator_linux.go

@@ -0,0 +1,33 @@
+// Copyright 2024 Matrix Origin
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build cgo
+
+package malloc
+
+/*
+#include <stdlib.h>
+#include <malloc.h>
+*/
+import "C"
+
+func init() {
+	// malloc tunings
+	C.mallopt(C.M_TOP_PAD, 0)        // no sbrk padding
+	C.mallopt(C.M_MMAP_THRESHOLD, 0) // always use mmap
+}
+
+func returnMallocMemoryToOS() {
+	C.malloc_trim(0)
+}

pkg/common/malloc/c_allocator_test.go

@@ -35,3 +35,12 @@ func FuzzCAllocator(f *testing.F) {
 		return NewCAllocator()
 	})
 }
+
+func TestCAllocatorReturnToOSThreshold(t *testing.T) {
+	allocator := NewCAllocator()
+	_, dec, err := allocator.Allocate(cMallocReturnToOSThreshold*2, NoHints)
+	if err != nil {
+		t.Fatal(err)
+	}
+	dec.Deallocate(NoHints)
+}

pkg/common/malloc/default.go

@@ -74,7 +74,7 @@ func newDefault(delta *Config) (allocator Allocator) {
 	}()
 
 	if config.Allocator == nil {
-		config.Allocator = ptrTo("mmap")
+		config.Allocator = ptrTo("c")
 	}
 
 	switch strings.ToLower(*config.Allocator) {

pkg/common/malloc/utils.go

@@ -15,6 +15,7 @@
 package malloc
 
 const (
+	KB = 1 << 10
 	MB = 1 << 20
 	GB = 1 << 30
 )