[scudo] Separate Fuchsia & Default SizeClassMap
The Fuchsia allocator config was using the default size class map.
This CL gives Fuchsia its own size class map and changes a couple of
things in the default one:
- make `SizeDelta` configurable in `Config` for a fixed size class map
as it currently is for a table size class map;
- switch `SizeDelta` to 0 for the default config, it allows for size
classes that allow for power of 2s, and overall better wrt pages
filling;
- increase the max number of caches pointers to 14 in the default,
this makes the transfer batch 64/128 bytes on 32/64-bit platforms,
which is cache-line friendly (previous size was 48/96 bytes).
The Fuchsia size class map remains untouched for now, this doesn't
impact Android which uses the table size class map.
Differential Revision: https://reviews.llvm.org/D102783
GitOrigin-RevId: 20c1f94220d938936867cb047fb6444a187626ba
diff --git a/size_class_map.h b/size_class_map.h
index 1948802..2736e99 100644
--- a/size_class_map.h
+++ b/size_class_map.h
@@ -64,12 +64,10 @@
static const u8 S = Config::NumBits - 1;
static const uptr M = (1UL << S) - 1;
- static const uptr SizeDelta = Chunk::getHeaderSize();
-
public:
static const u32 MaxNumCachedHint = Config::MaxNumCachedHint;
- static const uptr MaxSize = (1UL << Config::MaxSizeLog) + SizeDelta;
+ static const uptr MaxSize = (1UL << Config::MaxSizeLog) + Config::SizeDelta;
static const uptr NumClasses =
MidClass + ((Config::MaxSizeLog - Config::MidSizeLog) << S) + 1;
static_assert(NumClasses <= 256, "");
@@ -79,24 +77,22 @@
static uptr getSizeByClassId(uptr ClassId) {
DCHECK_NE(ClassId, BatchClassId);
if (ClassId <= MidClass)
- return (ClassId << Config::MinSizeLog) + SizeDelta;
+ return (ClassId << Config::MinSizeLog) + Config::SizeDelta;
ClassId -= MidClass;
const uptr T = MidSize << (ClassId >> S);
- return T + (T >> S) * (ClassId & M) + SizeDelta;
+ return T + (T >> S) * (ClassId & M) + Config::SizeDelta;
}
static u8 getSizeLSBByClassId(uptr ClassId) {
return u8(getLeastSignificantSetBitIndex(getSizeByClassId(ClassId)));
}
- static constexpr bool usesCompressedLSBFormat() {
- return false;
- }
+ static constexpr bool usesCompressedLSBFormat() { return false; }
static uptr getClassIdBySize(uptr Size) {
- if (Size <= SizeDelta + (1 << Config::MinSizeLog))
+ if (Size <= Config::SizeDelta + (1 << Config::MinSizeLog))
return 1;
- Size -= SizeDelta;
+ Size -= Config::SizeDelta;
DCHECK_LE(Size, MaxSize);
if (Size <= MidSize)
return (Size + MinSize - 1) >> Config::MinSizeLog;
@@ -227,12 +223,25 @@
static const uptr MinSizeLog = 5;
static const uptr MidSizeLog = 8;
static const uptr MaxSizeLog = 17;
- static const u32 MaxNumCachedHint = 10;
+ static const u32 MaxNumCachedHint = 14;
static const uptr MaxBytesCachedLog = 10;
+ static const uptr SizeDelta = 0;
};
typedef FixedSizeClassMap<DefaultSizeClassConfig> DefaultSizeClassMap;
+struct FuchsiaSizeClassConfig {
+ static const uptr NumBits = 3;
+ static const uptr MinSizeLog = 5;
+ static const uptr MidSizeLog = 8;
+ static const uptr MaxSizeLog = 17;
+ static const u32 MaxNumCachedHint = 10;
+ static const uptr MaxBytesCachedLog = 10;
+ static const uptr SizeDelta = Chunk::getHeaderSize();
+};
+
+typedef FixedSizeClassMap<FuchsiaSizeClassConfig> FuchsiaSizeClassMap;
+
struct AndroidSizeClassConfig {
#if SCUDO_WORDSIZE == 64U
static const uptr NumBits = 7;
@@ -285,6 +294,7 @@
static const uptr MaxSizeLog = 14;
static const u32 MaxNumCachedHint = 13;
static const uptr MaxBytesCachedLog = 10;
+ static const uptr SizeDelta = Chunk::getHeaderSize();
#else
static const uptr NumBits = 4;
static const uptr MinSizeLog = 3;
@@ -292,6 +302,7 @@
static const uptr MaxSizeLog = 14;
static const u32 MaxNumCachedHint = 14;
static const uptr MaxBytesCachedLog = 10;
+ static const uptr SizeDelta = Chunk::getHeaderSize();
#endif
};
