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Make realloc() go 100x faster on Linux/NetBSD

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Cosmopolitan now supports mremap(), which is only supported on Linux and
NetBSD. First, it allows memory mappings to be relocated without copying
them; this can dramatically speed up data structures like std::vector if
the array size grows larger than 256kb. The mremap() system call is also
10x faster than munmap() when shrinking large memory mappings.

There's now two functions, getpagesize() and getgransize() which help to
write portable code that uses mmap(MAP_FIXED). Alternative sysconf() may
be called with our new _SC_GRANSIZE. The madvise() system call now has a
better wrapper with improved documentation.
This commit is contained in:
Justine Tunney 2024-07-07 12:24:25 -07:00
parent 196942084b
commit f7780de24b
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GPG key ID: BE714B4575D6E328
71 changed files with 1301 additions and 640 deletions
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56
libc/calls/madvise-nt.c
View file

@ -16,61 +16,31 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/syscall-nt.internal.h"
#include "libc/calls/syscall_support-nt.internal.h"
#include "libc/nt/enum/offerpriority.h"
#include "libc/nt/memory.h"
#include "libc/nt/runtime.h"
#include "libc/nt/struct/memoryrangeentry.h"
#include "libc/sysv/consts/madv.h"
#include "libc/sysv/errfuns.h"
typedef bool32 (*__msabi PrefetchVirtualMemoryPtr)(
int64_t hProcess, uintptr_t NumberOfEntries,
struct NtMemoryRangeEntry *VirtualAddresses, uint32_t reserved_Flags);
textwindows static PrefetchVirtualMemoryPtr GetPrefetchVirtualMemory(void) {
static PrefetchVirtualMemoryPtr PrefetchVirtualMemory_;
if (!PrefetchVirtualMemory_) {
PrefetchVirtualMemory_ = /* win8.1+ */
GetProcAddressModule("Kernel32.dll", "PrefetchVirtualMemory");
}
return PrefetchVirtualMemory_;
}
typedef bool32 (*__msabi OfferVirtualMemoryPtr)(void *inout_VirtualAddress,
size_t Size, int Priority);
textwindows static OfferVirtualMemoryPtr GetOfferVirtualMemory(void) {
static OfferVirtualMemoryPtr OfferVirtualMemory_;
if (!OfferVirtualMemory_) {
OfferVirtualMemory_ = /* win8.1+ */
GetProcAddressModule("Kernel32.dll", "OfferVirtualMemory");
}
return OfferVirtualMemory_;
}
textwindows int sys_madvise_nt(void *addr, size_t length, int advice) {
if (advice == MADV_WILLNEED || advice == MADV_SEQUENTIAL) {
PrefetchVirtualMemoryPtr fn = GetPrefetchVirtualMemory();
if (fn) {
if (fn(GetCurrentProcess(), 1, &(struct NtMemoryRangeEntry){addr, length},
0)) {
return 0;
} else {
return __winerr();
}
if (!length)
return 0;
if (PrefetchVirtualMemory(GetCurrentProcess(), 1,
&(struct NtMemoryRangeEntry){addr, length}, 0)) {
return 0;
} else {
return enosys();
return __winerr();
}
} else if (advice == MADV_FREE) {
OfferVirtualMemoryPtr fn = GetOfferVirtualMemory();
if (fn) {
if (fn(addr, length, kNtVmOfferPriorityNormal)) {
return 0;
} else {
return __winerr();
}
if (!length)
return 0;
if (OfferVirtualMemory(addr, length, kNtVmOfferPriorityNormal)) {
return 0;
} else {
return enosys();
return __winerr();
}
} else {
return einval();