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mdbx: добавление опции MDBX_MMAP_USE_MS_ASYNC.

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Суть в избавлении от лишнего вызова msync(MS_ASYNC) в режимах
MDBX_WRITEMAP+MDBX_SAFE_NOSYNC и т.п.

Гипотетически могут быть системы/платформы, на которых изменения в
разделяемой памяти не видны другим процессам до вызова msync(MS_ASYNC)
и/или до этого вызова не будет инициироваться вытеснение/запись таких
страниц на диск.

Поэтому использование msync(MS_ASYNC) вынесено под опцию
MDBX_MMAP_USE_MS_ASYNC, которая по-умолчанию включена только на системах
с MDBX_MMAP_INCOHERENT_FILE_WRITE или MDBX_MMAP_INCOHERENT_CPU_CACHE.
This commit is contained in:
Леонид Юрьев (Leonid Yuriev) 2022-12-13 20:04:37 +03:00
parent 23fedf6bba
commit 07f2ccb752
2 changed files with 20 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
src/options.h
View File

@ -389,6 +389,16 @@
#error MDBX_MMAP_INCOHERENT_CPU_CACHE must be defined as 0 or 1 #error MDBX_MMAP_INCOHERENT_CPU_CACHE must be defined as 0 or 1
#endif /* MDBX_MMAP_INCOHERENT_CPU_CACHE */ #endif /* MDBX_MMAP_INCOHERENT_CPU_CACHE */
#ifndef MDBX_MMAP_USE_MS_ASYNC
#if MDBX_MMAP_INCOHERENT_FILE_WRITE || MDBX_MMAP_INCOHERENT_CPU_CACHE
#define MDBX_MMAP_USE_MS_ASYNC 1
#else
#define MDBX_MMAP_USE_MS_ASYNC 0
#endif
#elif !(MDBX_MMAP_USE_MS_ASYNC == 0 || MDBX_MMAP_USE_MS_ASYNC == 1)
#error MDBX_MMAP_USE_MS_ASYNC must be defined as 0 or 1
#endif /* MDBX_MMAP_USE_MS_ASYNC */
#ifndef MDBX_64BIT_ATOMIC #ifndef MDBX_64BIT_ATOMIC
#if MDBX_WORDBITS >= 64 || defined(DOXYGEN) #if MDBX_WORDBITS >= 64 || defined(DOXYGEN)
#define MDBX_64BIT_ATOMIC 1 #define MDBX_64BIT_ATOMIC 1

12
src/osal.c
View File

@ -1707,10 +1707,16 @@ MDBX_INTERNAL_FUNC int osal_thread_join(osal_thread_t thread) {
MDBX_INTERNAL_FUNC int osal_msync(const osal_mmap_t *map, size_t offset, MDBX_INTERNAL_FUNC int osal_msync(const osal_mmap_t *map, size_t offset,
size_t length, size_t length,
enum osal_syncmode_bits mode_bits) { enum osal_syncmode_bits mode_bits) {
if (!MDBX_MMAP_USE_MS_ASYNC && mode_bits == MDBX_SYNC_KICK)
return MDBX_SUCCESS;
void *ptr = ptr_disp(map->base, offset); void *ptr = ptr_disp(map->base, offset);
#if defined(_WIN32) || defined(_WIN64) #if defined(_WIN32) || defined(_WIN64)
if (!FlushViewOfFile(ptr, length)) if (!FlushViewOfFile(ptr, length))
return (int)GetLastError(); return (int)GetLastError();
if ((mode_bits & (MDBX_SYNC_DATA | MDBX_SYNC_IODQ)) &&
!FlushFileBuffers(map->fd))
return (int)GetLastError();
#else #else
#if defined(__linux__) || defined(__gnu_linux__) #if defined(__linux__) || defined(__gnu_linux__)
/* Since Linux 2.6.19, MS_ASYNC is in fact a no-op. The kernel properly /* Since Linux 2.6.19, MS_ASYNC is in fact a no-op. The kernel properly
@ -1718,6 +1724,7 @@ MDBX_INTERNAL_FUNC int osal_msync(const osal_mmap_t *map, size_t offset,
// //
// However, this behavior may be changed in custom kernels, // However, this behavior may be changed in custom kernels,
// so just leave such optimization to the libc discretion. // so just leave such optimization to the libc discretion.
// NOTE: The MDBX_MMAP_USE_MS_ASYNC must be defined to 1 for such cases.
// //
// assert(linux_kernel_version > 0x02061300); // assert(linux_kernel_version > 0x02061300);
// if (mode_bits == MDBX_SYNC_KICK) // if (mode_bits == MDBX_SYNC_KICK)
@ -1725,9 +1732,10 @@ MDBX_INTERNAL_FUNC int osal_msync(const osal_mmap_t *map, size_t offset,
#endif /* Linux */ #endif /* Linux */
if (msync(ptr, length, (mode_bits & MDBX_SYNC_DATA) ? MS_SYNC : MS_ASYNC)) if (msync(ptr, length, (mode_bits & MDBX_SYNC_DATA) ? MS_SYNC : MS_ASYNC))
return errno; return errno;
mode_bits &= ~MDBX_SYNC_DATA; if ((mode_bits & MDBX_SYNC_SIZE) && fsync(map->fd))
return errno;
#endif #endif
return osal_fsync(map->fd, mode_bits); return MDBX_SUCCESS;
} }
MDBX_INTERNAL_FUNC int osal_check_fs_rdonly(mdbx_filehandle_t handle, MDBX_INTERNAL_FUNC int osal_check_fs_rdonly(mdbx_filehandle_t handle,