add: enable FSCache around repo_read_index_preload()#6216
Open
dscho wants to merge 2 commits intogit-for-windows:mainfrom
Open
add: enable FSCache around repo_read_index_preload()#6216dscho wants to merge 2 commits intogit-for-windows:mainfrom
repo_read_index_preload()#6216dscho wants to merge 2 commits intogit-for-windows:mainfrom
Conversation
added 2 commits
April 28, 2026 09:40
Trace2 + GIT_TRACE_FSCACHE evidence on Windows ARM64 (Snapdragon X Elite, ReFS Dev Drive) shows that the heaviest `lstat()`-bound work in `git add` happens inside `repo_read_index_preload()`, which currently runs *before* `enable_fscache()` is called. Moving the enable up so the preload phase is wrapped lets the existing batched `NtQueryDirectoryFile()` cache cover the bulk of the lstat traffic. Signed-off-by: Anthony Shaw <anthonyshaw@microsoft.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Fix a copy-paste bug at the end of `cmd_add()`: the cleanup site called `enable_fscache(0)` again instead of `disable_fscache()`, leaking the refcount. Harmless in a one-shot process today, but it confuses the matching enable/disable contract that callers and reviewers expect. Signed-off-by: Anthony Shaw <anthonyshaw@microsoft.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
dscho
added a commit
to microsoft/git
that referenced
this pull request
Apr 28, 2026
…`vfs-2.54.0` (#902) This is a companion of #899 and git-for-windows#6216. Trace2 + GIT_TRACE_FSCACHE evidence on Windows ARM64 (Snapdragon X Elite, ReFS Dev Drive) shows that the heaviest lstat-bound work in git add happens inside repo_read_index_preload(), which currently runs before enable_fscache() is called. Moving the enable up so the preload phase is wrapped lets the existing batched NtQueryDirectoryFile cache cover the bulk of the lstat traffic. This patch gave me a ~30% performance improvement on a large git repo with a batched add. Also at the end of cmd_add(): the cleanup site called enable_fscache(0) again instead of disable_fscache(), leaking the refcount.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
This is a companion of microsoft#899.
Trace2 + GIT_TRACE_FSCACHE evidence on Windows ARM64 (Snapdragon X Elite, ReFS Dev Drive) shows that the heaviest lstat-bound work in git add happens inside repo_read_index_preload(), which currently runs before enable_fscache() is called. Moving the enable up so the preload phase is wrapped lets the existing batched NtQueryDirectoryFile cache cover the bulk of the lstat traffic. This patch gave me a ~30% performance improvement on a large git repo with a batched add.
Also at the end of cmd_add(): the cleanup site called enable_fscache(0) again instead of disable_fscache(), leaking the refcount.