project-base/server-skynet-source-3rd-jemalloc
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Avoid validating freshly mapped memory.

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Move validation of supposedly zeroed pages from chunk_alloc() to
chunk_recycle().  There is little point to validating newly mapped
memory returned by chunk_alloc_mmap(), and memory that comes from sbrk()
is explicitly zeroed, so there is little risk to assuming that
chunk_alloc_dss() actually does the zeroing properly.

This relaxation of validation can make a big difference to application
startup time and overall system usage on platforms that use jemalloc as
the system allocator (namely FreeBSD).

Submitted by Ian Lepore <ian@FreeBSD.org>.
This commit is contained in:
Jason Evans 2013-01-21 19:56:34 -08:00
parent 13e4e24c42
commit 14a2c6a698
1 changed files with 17 additions and 17 deletions
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34
src/chunk.c
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@ -78,6 +78,9 @@ chunk_recycle(extent_tree_t *chunks_szad, extent_tree_t *chunks_ad, size_t size,
assert(node->size >= leadsize + size);
trailsize = node->size - leadsize - size;
ret = (void *)((uintptr_t)node->addr + leadsize);
zeroed = node->zeroed;
if (zeroed)
*zero = true;
/* Remove node from the tree. */
extent_tree_szad_remove(chunks_szad, node);
extent_tree_ad_remove(chunks_ad, node);
@ -114,17 +117,22 @@ chunk_recycle(extent_tree_t *chunks_szad, extent_tree_t *chunks_ad, size_t size,
}
malloc_mutex_unlock(&chunks_mtx);
zeroed = false;
if (node != NULL) {
if (node->zeroed) {
zeroed = true;
*zero = true;
}
if (node != NULL)
base_node_dealloc(node);
}
VALGRIND_MAKE_MEM_UNDEFINED(ret, size);
if (zeroed == false && *zero)
memset(ret, 0, size);
if (*zero) {
if (zeroed == false)
memset(ret, 0, size);
else if (config_debug) {
size_t i;
size_t *p = (size_t *)(uintptr_t)ret;
VALGRIND_MAKE_MEM_DEFINED(ret, size);
for (i = 0; i < size / sizeof(size_t); i++)
assert(p[i] == 0);
VALGRIND_MAKE_MEM_UNDEFINED(ret, size);
}
}
return (ret);
}
@ -193,14 +201,6 @@ label_return:
if (config_prof && opt_prof && opt_prof_gdump && gdump)
prof_gdump();
}
if (config_debug && *zero && ret != NULL) {
size_t i;
size_t *p = (size_t *)(uintptr_t)ret;
VALGRIND_MAKE_MEM_DEFINED(ret, size);
for (i = 0; i < size / sizeof(size_t); i++)
assert(p[i] == 0);
}
assert(CHUNK_ADDR2BASE(ret) == ret);
return (ret);
}