diff options
author | Neeraj Singh <neerajsi@microsoft.com> | 2022-03-11 01:43:20 +0300 |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2022-03-11 02:10:22 +0300 |
commit | abf38abec201cded6094801766d69e11a6c112b6 (patch) | |
tree | f1258b40f52f600be015a365ae5e57ed3b977a33 /compat | |
parent | 19d3f228c8df7e946278c96fb52acf1cea0f6a7a (diff) |
core.fsyncmethod: add writeout-only mode
This commit introduces the `core.fsyncMethod` configuration
knob, which can currently be set to `fsync` or `writeout-only`.
The new writeout-only mode attempts to tell the operating system to
flush its in-memory page cache to the storage hardware without issuing a
CACHE_FLUSH command to the storage controller.
Writeout-only fsync is significantly faster than a vanilla fsync on
common hardware, since data is written to a disk-side cache rather than
all the way to a durable medium. Later changes in this patch series will
take advantage of this primitive to implement batching of hardware
flushes.
When git_fsync is called with FSYNC_WRITEOUT_ONLY, it may fail and the
caller is expected to do an ordinary fsync as needed.
On Apple platforms, the fsync system call does not issue a CACHE_FLUSH
directive to the storage controller. This change updates fsync to do
fcntl(F_FULLFSYNC) to make fsync actually durable. We maintain parity
with existing behavior on Apple platforms by setting the default value
of the new core.fsyncMethod option.
Signed-off-by: Neeraj Singh <neerajsi@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'compat')
-rw-r--r-- | compat/mingw.h | 3 | ||||
-rw-r--r-- | compat/win32/flush.c | 28 |
2 files changed, 31 insertions, 0 deletions
diff --git a/compat/mingw.h b/compat/mingw.h index c9a52ad64a..6074a3d3ce 100644 --- a/compat/mingw.h +++ b/compat/mingw.h @@ -329,6 +329,9 @@ int mingw_getpagesize(void); #define getpagesize mingw_getpagesize #endif +int win32_fsync_no_flush(int fd); +#define fsync_no_flush win32_fsync_no_flush + struct rlimit { unsigned int rlim_cur; }; diff --git a/compat/win32/flush.c b/compat/win32/flush.c new file mode 100644 index 0000000000..291f90ea94 --- /dev/null +++ b/compat/win32/flush.c @@ -0,0 +1,28 @@ +#include "git-compat-util.h" +#include <winternl.h> +#include "lazyload.h" + +int win32_fsync_no_flush(int fd) +{ + IO_STATUS_BLOCK io_status; + +#define FLUSH_FLAGS_FILE_DATA_ONLY 1 + + DECLARE_PROC_ADDR(ntdll.dll, NTSTATUS, NTAPI, NtFlushBuffersFileEx, + HANDLE FileHandle, ULONG Flags, PVOID Parameters, ULONG ParameterSize, + PIO_STATUS_BLOCK IoStatusBlock); + + if (!INIT_PROC_ADDR(NtFlushBuffersFileEx)) { + errno = ENOSYS; + return -1; + } + + memset(&io_status, 0, sizeof(io_status)); + if (NtFlushBuffersFileEx((HANDLE)_get_osfhandle(fd), FLUSH_FLAGS_FILE_DATA_ONLY, + NULL, 0, &io_status)) { + errno = EINVAL; + return -1; + } + + return 0; +} |