Cheri-research/snmalloc
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Change default chunksize to 1MiB (#229)

Browse Source 
This change makes the original 16MiB option not the common option.

It also changes the names of the defines to
  SNMALLOC_USE_LARGE_CHUNKS
  SNMALLOC_USE_SMALL_CHUNKS

The second should be set for Open Enclave configuration, and results in
256KiB chunk sizes.  The first being set builds the original 16MiB chunk
sizes.  If neither is set, then we default to 1MiB chunk sizes.
This commit is contained in:
Matthew Parkinson
2020-07-09 13:22:32 +01:00
committed by GitHub
parent 8d1f3c3046
commit 4e1f5829a7
6 changed files with 29 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
src/mem/allocconfig.h
View File

@@ -41,29 +41,21 @@ namespace snmalloc
// Specifies smaller slab and super slab sizes for address space
// constrained scenarios.
static constexpr size_t ADDRESS_SPACE_CONSTRAINED =
#ifdef IS_ADDRESS_SPACE_CONSTRAINED
true
#else
static constexpr size_t USE_LARGE_CHUNKS =
#ifdef SNMALLOC_USE_LARGE_CHUNKS
// In 32 bit uses smaller superslab.
(!bits::is64())
#endif
;
// Specifies even smaller slab and super slab sizes for open enclave.
static constexpr size_t REALLY_ADDRESS_SPACE_CONSTRAINED =
#ifdef IS_REALLY_ADDRESS_SPACE_CONSTRAINED
true
(bits::is64())
#else
false
#endif
;
static constexpr size_t RESERVE_MULTIPLE =
#ifdef USE_RESERVE_MULTIPLE
USE_RESERVE_MULTIPLE
// Specifies even smaller slab and super slab sizes for open enclave.
static constexpr size_t USE_SMALL_CHUNKS =
#ifdef SNMALLOC_USE_SMALL_CHUNKS
true
#else
bits::is64() ? 16 : 2
false
#endif
;
@@ -109,9 +101,8 @@ namespace snmalloc
static constexpr size_t MIN_ALLOC_BITS = bits::ctz_const(MIN_ALLOC_SIZE);
// Slabs are 64 KiB unless constrained to 16 KiB.
static constexpr size_t SLAB_BITS = REALLY_ADDRESS_SPACE_CONSTRAINED ?
13 :
(ADDRESS_SPACE_CONSTRAINED ? 14 : 16);
static constexpr size_t SLAB_BITS =
USE_SMALL_CHUNKS ? 13 : (USE_LARGE_CHUNKS ? 16 : 14);
static constexpr size_t SLAB_SIZE = 1 << SLAB_BITS;
static constexpr size_t SLAB_MASK = ~(SLAB_SIZE - 1);
@@ -119,12 +110,11 @@ namespace snmalloc
// a byte, so the maximum count is 256. This must be a power of two to
// allow fast masking to find a superslab start address.
static constexpr size_t SLAB_COUNT_BITS =
REALLY_ADDRESS_SPACE_CONSTRAINED ? 5 : (ADDRESS_SPACE_CONSTRAINED ? 6 : 8);
USE_SMALL_CHUNKS ? 5 : (USE_LARGE_CHUNKS ? 8 : 6);
static constexpr size_t SLAB_COUNT = 1 << SLAB_COUNT_BITS;
static constexpr size_t SUPERSLAB_SIZE = SLAB_SIZE * SLAB_COUNT;
static constexpr size_t SUPERSLAB_MASK = ~(SUPERSLAB_SIZE - 1);
static constexpr size_t SUPERSLAB_BITS = SLAB_BITS + SLAB_COUNT_BITS;
static constexpr size_t RESERVE_SIZE = SUPERSLAB_SIZE * RESERVE_MULTIPLE;
static_assert((1ULL << SUPERSLAB_BITS) == SUPERSLAB_SIZE, "Sanity check");