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Improve heuristic for committing memory with virtual.alloc_from_memory_block

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gingerBill
2023-08-15 15:42:28 +01:00
parent 8d673789be
commit 52318d0e0e
1 changed files with 12 additions and 5 deletions
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17
core/mem/virtual/virtual.odin
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@@ -2,6 +2,8 @@ package mem_virtual
import "core:mem"
import "core:intrinsics"
import "core:runtime"
_ :: runtime
DEFAULT_PAGE_SIZE := uint(4096)
@@ -83,7 +85,7 @@ memory_block_alloc :: proc(committed, reserved: uint, flags: Memory_Block_Flags)
do_protection := false
if .Overflow_Protection in flags { // overflow protection
rounded_size := align_formula(uint(reserved), page_size)
rounded_size := reserved
total_size = uint(rounded_size + 2*page_size)
base_offset = uintptr(page_size + rounded_size - uint(reserved))
protect_offset = uintptr(page_size + rounded_size)
@@ -92,14 +94,14 @@ memory_block_alloc :: proc(committed, reserved: uint, flags: Memory_Block_Flags)
pmblock := platform_memory_alloc(0, total_size) or_return
pmblock.block.base = ([^]byte)(uintptr(pmblock) + base_offset)
pmblock.block.base = ([^]byte)(pmblock)[base_offset:]
platform_memory_commit(pmblock, uint(base_offset) + committed) or_return
// Should be zeroed
assert(pmblock.block.used == 0)
assert(pmblock.block.prev == nil)
if do_protection {
protect(rawptr(uintptr(pmblock) + protect_offset), page_size, Protect_No_Access)
protect(([^]byte)(pmblock)[protect_offset:], page_size, Protect_No_Access)
}
pmblock.block.committed = committed
@@ -125,7 +127,11 @@ alloc_from_memory_block :: proc(block: ^Memory_Block, min_size, alignment: uint)
if block.committed - block.used < size {
pmblock := (^Platform_Memory_Block)(block)
base_offset := uint(uintptr(pmblock.block.base) - uintptr(pmblock))
platform_total_commit := base_offset + block.used + size
// NOTE(bill): [Heuristic] grow the commit size larger than needed
// TODO(bill): determine a better heuristic for this behaviour
extra_size := max(size, block.committed>>2)
platform_total_commit := base_offset + block.used + extra_size
platform_total_commit = align_formula(platform_total_commit, DEFAULT_PAGE_SIZE)
platform_total_commit = min(platform_total_commit, pmblock.reserved)
@@ -136,8 +142,9 @@ alloc_from_memory_block :: proc(block: ^Memory_Block, min_size, alignment: uint)
pmblock.committed = platform_total_commit
block.committed = pmblock.committed - base_offset
}
return nil
return
}
if block == nil {