qiurui
/
glibc
mirror of git://sourceware.org/git/glibc.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

malloc: Improve mmap interface 

Add mmap_set_chunk() to create a new chunk from an mmap block.
Remove set_mmap_is_hp() since it is done inside mmap_set_chunk().
Rename prev_size_mmap() to mmap_base_offset().  Cleanup comments.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Wilco Dijkstra 2025-10-01 17:43:11 +00:00
parent adbd3ba137
commit 88de32a070
1 changed files with 21 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
malloc/malloc.c
View File

@ -1477,26 +1477,19 @@ tag_new_usable (void *ptr)
return ptr;
}
/* HP page used for an mmap()'ed chunk. */
/* Huge page used for an mmap chunk. */
#define MMAP_HP 0x1
/* Check for HP usage from an mmap()'ed chunk. */
/* Return whether an mmap chunk uses huge pages. */
static __always_inline bool
mmap_is_hp (mchunkptr p)
{
return prev_size (p) & MMAP_HP;
}
/* Set HP advised field for an mmap()'ed chunk. */
static __always_inline void
set_mmap_is_hp (mchunkptr p)
{
prev_size (p) |= MMAP_HP;
}
/* Get an mmap()ed chunk's offset, ignoring huge page bits. */
/* Return the mmap chunk's offset from mmap base. */
static __always_inline size_t
prev_size_mmap (mchunkptr p)
mmap_base_offset (mchunkptr p)
{
return prev_size (p) & ~MMAP_HP;
}
@ -1505,14 +1498,24 @@ prev_size_mmap (mchunkptr p)
static __always_inline uintptr_t
mmap_base (mchunkptr p)
{
return (uintptr_t) p - prev_size_mmap (p);
return (uintptr_t) p - mmap_base_offset (p);
}
/* Return total mmap size of a chunk with IS_MMAPPED set. */
static __always_inline size_t
mmap_size (mchunkptr p)
{
return prev_size_mmap (p) + chunksize (p) + CHUNK_HDR_SZ;
return mmap_base_offset (p) + chunksize (p) + CHUNK_HDR_SZ;
}
/* Return a new chunk from an mmap. */
static __always_inline mchunkptr
mmap_set_chunk (uintptr_t mmap_base, size_t mmap_size, size_t offset, bool is_hp)
{
mchunkptr p = (mchunkptr) (mmap_base + offset);
prev_size (p) = offset | (is_hp ? MMAP_HP : 0);
set_head (p, (mmap_size - offset - CHUNK_HDR_SZ) | IS_MMAPPED);
return p;
}
/*
@ -2458,15 +2461,7 @@ sysmalloc_mmap (INTERNAL_SIZE_T nb, size_t pagesize, int extra_flags)
__set_vma_name (mm, size, " glibc: malloc");
/* Store offset to start of mmap in prev_size. */
mchunkptr p = (mchunkptr) (mm + padding);
set_prev_size (p, padding);
set_head (p, (size - padding - CHUNK_HDR_SZ) | IS_MMAPPED);
/* Must also check whether huge pages were used in the mmap call
and this is not the fallback call after using huge pages failed */
if (__glibc_unlikely (extra_flags & mp_.hp_flags))
set_mmap_is_hp (p);
mchunkptr p = mmap_set_chunk ((uintptr_t)mm, size, padding, extra_flags != 0);
/* update statistics */
int new = atomic_fetch_add_relaxed (&mp_.n_mmaps, 1) + 1;
@ -3038,8 +3033,9 @@ munmap_chunk (mchunkptr p)
static mchunkptr
mremap_chunk (mchunkptr p, size_t new_size)
{
size_t pagesize = mmap_is_hp (p) ? mp_.hp_pagesize : GLRO (dl_pagesize);
INTERNAL_SIZE_T offset = prev_size_mmap (p);
bool is_hp = mmap_is_hp (p);
size_t pagesize = is_hp ? mp_.hp_pagesize : GLRO (dl_pagesize);
INTERNAL_SIZE_T offset = mmap_base_offset (p);
INTERNAL_SIZE_T size = chunksize (p);
char *cp;
@ -3067,12 +3063,7 @@ mremap_chunk (mchunkptr p, size_t new_size)
madvise_thp (cp, new_size);
p = (mchunkptr) (cp + offset);
assert (!misaligned_chunk (p));
assert (prev_size_mmap (p) == offset);
set_head (p, (new_size - offset - CHUNK_HDR_SZ) | IS_MMAPPED);
p = mmap_set_chunk ((uintptr_t) cp, new_size, offset, is_hp);
INTERNAL_SIZE_T new;
new = atomic_fetch_add_relaxed (&mp_.mmapped_mem, new_size - size - offset)