The threading model for fscache has been to have a single, global cache.
This puts requirements on it to be thread safe so that callers like
preload-index can call it from multiple threads. This was implemented
with a single mutex and completion events which introduces contention
between the calling threads.
Simplify the threading model by making fscache thread specific. This allows
us to remove the global mutex and synchronization events entirely and instead
associate a fscache with every thread that requests one. This works well with
the current multi-threading which divides the cache entries into blocks with
a separate thread processing each block.
At the end of each worker thread, if there is a fscache on the primary
thread, merge the cached results from the worker into the primary thread
cache. This enables us to reuse the cache later especially when scanning for
untracked files.
In testing, this reduced the time spent in preload_index() by about 25% and
also reduced the CPU utilization significantly. On a repo with ~200K files,
it reduced overall status times by ~12%.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Update enable_fscache() to take an optional initial size parameter which is
used to initialize the hashmap so that it can avoid having to rehash as
additional entries are added.
Add a separate disable_fscache() macro to make the code clearer and easier
to read.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Track fscache hits and misses for lstat and opendir requests. Reporting of
statistics is done when the cache is disabled for the last time and freed
and is only reported if GIT_TRACE_FSCACHE is set.
Sample output is:
11:33:11.836428 compat/win32/fscache.c:433 fscache: lstat 3775, opendir 263, total requests/misses 4052/269
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Use FindFirstFileExW with FindExInfoBasic to avoid forcing NTFS to look up
the short name. Also switch to a larger (64K vs 4K) buffer using
FIND_FIRST_EX_LARGE_FETCH to minimize round trips to the kernel.
In a repo with ~200K files, this drops warm cache status times from 3.19
seconds to 2.67 seconds for a 16% savings.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
This is retry of #1419.
I added flush_fscache macro to flush cached stats after disk writing
with tests for regression reported in #1438 and #1442.
git checkout checks each file path in sorted order, so cache flushing does not
make performance worse unless we have large number of modified files in
a directory containing many files.
Using chromium repository, I tested `git checkout .` performance when I
delete 10 files in different directories.
With this patch:
TotalSeconds: 4.307272
TotalSeconds: 4.4863595
TotalSeconds: 4.2975562
Avg: 4.36372923333333
Without this patch:
TotalSeconds: 20.9705431
TotalSeconds: 22.4867685
TotalSeconds: 18.8968292
Avg: 20.7847136
I confirmed this patch passed all tests in t/ with core_fscache=1.
Signed-off-by: Takuto Ikuta <tikuta@chromium.org>
Make fscache_enabled() function public rather than static.
Remove unneeded fscache_is_enabled() function.
Change is_fscache_enabled() macro to call fscache_enabled().
is_fscache_enabled() now takes a pathname so that the answer
is more precise and mean "is fscache enabled for this pathname",
since fscache only stores repo-relative paths and not absolute
paths, we can avoid attempting lookups for absolute paths.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Teach read_directory_recursive() and add_excludes() to
be aware of optional fscache and avoid trying to open()
and fstat() non-existant ".gitignore" files in every
directory in the worktree.
The current code in add_excludes() calls open() and then
fstat() for a ".gitignore" file in each directory present
in the worktree. Change that when fscache is enabled to
call lstat() first and if present, call open().
This seems backwards because both lstat needs to do more
work than fstat. But when fscache is enabled, fscache will
already know if the .gitignore file exists and can completely
avoid the IO calls. This works because of the lstat diversion
to mingw_lstat when fscache is enabled.
This reduced status times on a 350K file enlistment of the
Windows repo on a NVMe SSD by 0.25 seconds.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Teach FSCACHE to remember "not found" directories.
This is a performance optimization.
FSCACHE is a performance optimization available for Windows. It
intercepts Posix-style lstat() calls into an in-memory directory
using FindFirst/FindNext. It improves performance on Windows by
catching the first lstat() call in a directory, using FindFirst/
FindNext to read the list of files (and attribute data) for the
entire directory into the cache, and short-cut subsequent lstat()
calls in the same directory. This gives a major performance
boost on Windows.
However, it does not remember "not found" directories. When STATUS
runs and there are missing directories, the lstat() interception
fails to find the parent directory and simply return ENOENT for the
file -- it does not remember that the FindFirst on the directory
failed. Thus subsequent lstat() calls in the same directory, each
re-attempt the FindFirst. This completely defeats any performance
gains.
This can be seen by doing a sparse-checkout on a large repo and
then doing a read-tree to reset the skip-worktree bits and then
running status.
This change reduced status times for my very large repo by 60%.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
If multiple threads access a directory that is not yet in the cache, the
directory will be loaded by each thread. Only one of the results is added
to the cache, all others are leaked. This wastes performance and memory.
On cache miss, add a future object to the cache to indicate that the
directory is currently being loaded. Subsequent threads register themselves
with the future object and wait. When the first thread has loaded the
directory, it replaces the future object with the result and notifies
waiting threads.
Signed-off-by: Karsten Blees <blees@dcon.de>
Checking the work tree status is quite slow on Windows, due to slow
`lstat()` emulation (git calls `lstat()` once for each file in the
index). Windows operating system APIs seem to be much better at scanning
the status of entire directories than checking single files.
Add an `lstat()` implementation that uses a cache for lstat data. Cache
misses read the entire parent directory and add it to the cache.
Subsequent `lstat()` calls for the same directory are served directly
from the cache.
Also implement `opendir()`/`readdir()`/`closedir()` so that they create
and use directory listings in the cache.
The cache doesn't track file system changes and doesn't plug into any
modifying file APIs, so it has to be explicitly enabled for git functions
that don't modify the working copy.
Note: in an earlier version of this patch, the cache was always active and
tracked file system changes via ReadDirectoryChangesW. However, this was
much more complex and had negative impact on the performance of modifying
git commands such as 'git checkout'.
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a macro to mark code sections that only read from the file system,
along with a config option and documentation.
This facilitates implementation of relatively simple file system level
caches without the need to synchronize with the file system.
Enable read-only sections for 'git status' and preload_index.
Signed-off-by: Karsten Blees <blees@dcon.de>
Emulating the POSIX lstat API on Windows via GetFileAttributes[Ex] is quite
slow. Windows operating system APIs seem to be much better at scanning the
status of entire directories than checking single files. A caching
implementation may improve performance by bulk-reading entire directories
or reusing data obtained via opendir / readdir.
Make the lstat implementation pluggable so that it can be switched at
runtime, e.g. based on a config option.
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Emulating the POSIX `dirent` API on Windows via
`FindFirstFile()`/`FindNextFile()` is pretty staightforward, however,
most of the information provided in the `WIN32_FIND_DATA` structure is
thrown away in the process. A more sophisticated implementation may
cache this data, e.g. for later reuse in calls to `lstat()`.
Make the `dirent` implementation pluggable so that it can be switched at
runtime, e.g. based on a config option.
Define a base DIR structure with pointers to `readdir()`/`closedir()`
that match the `opendir()` implementation (similar to vtable pointers in
Object-Oriented Programming). Define `readdir()`/`closedir()` so that
they call the function pointers in the `DIR` structure. This allows to
choose the `opendir()` implementation on a call-by-call basis.
Make the fixed-size `dirent.d_name` buffer a flex array, as `d_name` may
be implementation specific (e.g. a caching implementation may allocate a
`struct dirent` with _just_ the size needed to hold the `d_name` in
question).
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
We will use them in the upcoming "FSCache" patches (to accelerate
sequential lstat() calls).
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The first three commits are rebased versions of those in gitgitgadget/git#1215. These allow the following:
1. Fix `git config --global foo.bar <path>` from allowing the `<path>`. As a bonus, users with a config value starting with `/` will not get a warning about "old-style" paths needing a "`%(prefix)/`".
2. When in WSL, the path starts with `/` so it needs to be interpolated properly. Update the warning to include `%(prefix)/` to get the right value for WSL users. (This is specifically for using Git for Windows from Git Bash, but in a WSL directory.)
3. When using WSL, the ownership check fails and reports an error message. This is noisy, and happens even if the user has marked the path with `safe.directory`. Remove that error message.
This topic branch teaches `git clean` to respect NTFS junctions and Unix
bind mounts: it will now stop at those boundaries.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Newer compiler versions, like GCC 10 and Clang 12, have built-in
functions for bswap32 and bswap64. This comes in handy, for example,
when targeting CLANGARM64 on Windows, which would not be supported
without this logic.
Signed-off-by: Dennis Ameling <dennis@dennisameling.com>
Setting `MIMALLOC_SHOW_STATS` to ask mimalloc to print out something
after the process is done is the easiest way to verify that a
mimalloc-enabled Git is running.
So it better work and not try to write to a Win32 Console when it got a
regular file handle instead or, as is the case in Git for Windows'
regular Git Bash window, an emulated pseudo terminal.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Instead, load the `BCryptGenRandom()` function dynamically. When
needed. If needed.
This is necessary because the start-up cost of Git processes spent on
loading dynamic libraries is non-negligible.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Instead, load the `GetProcessMemoryInfo()` function dynamically. When
needed. If needed.
This is necessary because the start-up cost of Git processes spent on
loading dynamic libraries is non-negligible.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
We want to compile mimalloc's source code as part of Git, rather than
requiring the code to be built as an external library: mimalloc uses a
CMake-based build, which is not necessarily easy to integrate into the
flavors of Git for Windows (which will be the main benefitting port).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Atomic append on windows is only supported on local disk files, and it may
cause errors in other situations, e.g. network file system. If that is the
case, this config option should be used to turn atomic append off.
Co-Authored-By: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: 孙卓识 <sunzhuoshi@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
NtQueryObject under Wine can return a success but fill out no name.
In those situations, Wine will set Buffer to NULL, and set result to
the sizeof(OBJECT_NAME_INFORMATION).
Running a command such as
echo "$(git.exe --version 2>/dev/null)"
will crash due to a NULL pointer dereference when the code attempts to
null terminate the buffer, although, weirdly, removing the subshell or
redirecting stdout to a file will not trigger the crash.
Code has been added to also check Buffer and Length to ensure the check
is as robust as possible due to the current behavior being fragile at
best, and could potentially change in the future
This code is based on the behavior of NtQueryObject under wine and
reactos.
Signed-off-by: Christopher Degawa <ccom@randomderp.com>
For Windows builds >= 15063 set $env:TERM to "xterm-256color" instead of
"cygwin" because they have a more capable console system that supports
this. Also set $env:COLORTERM="truecolor" if unset.
$env:TERM is initialized so that ANSI colors in color.c work, see
29a3963484 (Win32: patch Windows environment on startup, 2012-01-15).
See git-for-windows/git#3629 regarding problems caused by always setting
$env:TERM="cygwin".
This is the same heuristic used by the Cygwin runtime.
Signed-off-by: Rafael Kitover <rkitover@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
In the case of Git for Windows (say, in a Git Bash window) running in a
Windows Subsystem for Linux (WSL) directory, the GetNamedSecurityInfoW()
call in is_path_owned_By_current_side() returns an error code other than
ERROR_SUCCESS. This is consistent behavior across this boundary.
In these cases, the owner would always be different because the WSL
owner is a different entity than the Windows user.
The change here is to suppress the error message that looks like this:
error: failed to get owner for '//wsl.localhost/...' (1)
Before this change, this warning happens for every Git command,
regardless of whether the directory is marked with safe.directory.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
The `GetNumaProcessorNode()` symbol is not defined in Nano Server's DLLs
(because that function is long deprecated). This caused Git no longer to
work on Nano Server.
Instead of importing it statically, try to import it dynamically, and
fall back gracefully if it cannot be loaded.
This fixes https://github.com/git-for-windows/git/issues/4052
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This commit imports mimalloc's source code as per v2.0.6, fetched from
the tag at https://github.com/microsoft/mimalloc.
The .c files are from the src/ subdirectory, and the .h files from the
include/ subdirectory. We will subsequently modify the source code to
accommodate building within Git's context.
Since we plan on using the `mi_*()` family of functions, we skip the
C++-specific source code, some POSIX compliant functions to interact
with mimalloc, and the code that wants to support auto-magic overriding
of the `malloc()` function (mimalloc-new-delete.h, alloc-posix.c,
mimalloc-override.h, alloc-override.c, alloc-override-osx.c,
alloc-override-win.c and static.c).
To appease the `check-whitespace` job of Git's Continuous Integration,
this commit was washed one time via `git rebase --whitespace=fix`.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The mingw-w64 GCC seems to link implicitly to libwinpthread, which does
implement a pthread emulation (that is more complete than Git's). Let's
keep preferring Git's.
To avoid linker errors where it thinks that the `pthread_self` and the
`pthread_create` symbols are defined twice, let's give our version a
`win32_` prefix, just like we already do for `pthread_join()`.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
We used to have that `make vcxproj` hack, but a hack it is. In the
meantime, we have a much cleaner solution: using CMake, either
explicitly, or even more conveniently via Visual Studio's built-in CMake
support (simply open Git's top-level directory via File>Open>Folder...).
Let's let the `README` reflect this.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
