When core.fsync includes loose-object, we issue an fsync after every written object. For a 'git-add' or similar command that adds a lot of files to the repo, the costs of these fsyncs adds up. One major factor in this cost is the time it takes for the physical storage controller to flush its caches to durable media. This series takes advantage of the writeout-only mode of git_fsync to issue OS cache writebacks for all of the objects being added to the repository followed by a single fsync to a dummy file, which should trigger a filesystem log flush and storage controller cache flush. This mechanism is known to be safe on common Windows filesystems and expected to be safe on macOS. Some linux filesystems, such as XFS, will probably do the right thing as well. See [1] for previous discussion on the predecessor of this patch series. This series is important on Windows, where loose-objects are included in the fsync set by default in Git-For-Windows. In this series, I'm also setting the default mode for Windows to turn on loose object fsyncing with batch mode, so that we can get CI coverage of the actual git-for-windows configuration upstream. We still don't actually issue fsyncs for the test suite since GIT_TEST_FSYNC is set to 0, but we exercise all of the surrounding batch mode code. This work is based on 'seen' at 367f447f0f0cf39e9830c865e8373e42a3c45303. It's dependent on ns/core-fsyncmethod. [1] https://lore.kernel.org/git/2c1ddef6057157d85da74a7274e03eacf0374e45.1629856293.git.gitgitgadget@xxxxxxxxx/ Neeraj Singh (7): bulk-checkin: rename 'state' variable and separate 'plugged' boolean core.fsyncmethod: batched disk flushes for loose-objects update-index: use the bulk-checkin infrastructure unpack-objects: use the bulk-checkin infrastructure core.fsync: use batch mode and sync loose objects by default on Windows core.fsyncmethod: tests for batch mode core.fsyncmethod: performance tests for add and stash Documentation/config/core.txt | 5 ++ builtin/unpack-objects.c | 3 ++ builtin/update-index.c | 6 +++ bulk-checkin.c | 89 +++++++++++++++++++++++++++++++---- bulk-checkin.h | 2 + cache.h | 12 ++++- compat/mingw.h | 3 ++ config.c | 4 +- git-compat-util.h | 2 + object-file.c | 2 + t/lib-unique-files.sh | 36 ++++++++++++++ t/perf/p3700-add.sh | 59 +++++++++++++++++++++++ t/perf/p3900-stash.sh | 62 ++++++++++++++++++++++++ t/perf/perf-lib.sh | 4 +- t/t3700-add.sh | 22 +++++++++ t/t3903-stash.sh | 17 +++++++ t/t5300-pack-object.sh | 32 ++++++++----- 17 files changed, 335 insertions(+), 25 deletions(-) create mode 100644 t/lib-unique-files.sh create mode 100755 t/perf/p3700-add.sh create mode 100755 t/perf/p3900-stash.sh base-commit: 367f447f0f0cf39e9830c865e8373e42a3c45303 Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1134%2Fneerajsi-msft%2Fns%2Fbatched-fsync-v1 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1134/neerajsi-msft/ns/batched-fsync-v1 Pull-Request: https://github.com/gitgitgadget/git/pull/1134 -- gitgitgadget
