The unpack_trees() API used in checking out a branch and merging
walks one or more trees along with the index. When the cache-tree
in the index tells us that we are walking a tree whose flattened
contents is known (i.e. matches a span in the index), as linearly
scanning a span in the index is much more efficient than having to
open tree objects recursively and listing their entries, the walk
can be optimized, which is done in this topic.
* nd/unpack-trees-with-cache-tree:
Document update for nd/unpack-trees-with-cache-tree
cache-tree: verify valid cache-tree in the test suite
unpack-trees: add missing cache invalidation
unpack-trees: reuse (still valid) cache-tree from src_index
unpack-trees: reduce malloc in cache-tree walk
unpack-trees: optimize walking same trees with cache-tree
unpack-trees: add performance tracing
trace.h: support nested performance tracing
Performance measurements are listed right now as a flat list, which is
fine when we measure big blocks. But when we start adding more and
more measurements, some of them could be just part of a bigger
measurement and a flat list gives a wrong impression that they are
executed at the same level instead of nested.
Add trace_performance_enter() and trace_performance_leave() to allow
indent these nested measurements. For now it does not help much
because the only nested thing is (lazy) name hash initialization
(e.g. called in diff-index from "git status"). This will help more
because I'm going to add some more tracing that's actually nested.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Make the match_patchspec API and friends take an index_state instead
of assuming the_index in dir.c. All external call sites are converted
blindly to keep the patch simple and retain current behavior.
Individual call sites may receive further updates to use the right
index instead of the_index.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
All the known heavy code blocks are measured (except object database
access). This should help identify if an optimization is effective or
not. An unoptimized git-status would give something like below:
0.001791141 s: read cache ...
0.004011363 s: preload index
0.000516161 s: refresh index
0.003139257 s: git command: ... 'status' '--porcelain=2'
0.006788129 s: diff-files
0.002090267 s: diff-index
0.001885735 s: initialize name hash
0.032013138 s: read directory
0.051781209 s: git command: './git' 'status'
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When the index is read from disk, the fsmonitor index extension is used
to flag the last known potentially dirty index entries. The registered
core.fsmonitor command is called with the time the index was last
updated and returns the list of files changed since that time. This list
is used to flag any additional dirty cache entries and untracked cache
directories.
We can then use this valid state to speed up preload_index(),
ie_match_stat(), and refresh_cache_ent() as they do not need to lstat()
files to detect potential changes for those entries marked
CE_FSMONITOR_VALID.
In addition, if the untracked cache is turned on valid_cached_dir() can
skip checking directories for new or changed files as fsmonitor will
invalidate the cache only for those directories that have been
identified as having potential changes.
To keep the CE_FSMONITOR_VALID state accurate during git operations;
when git updates a cache entry to match the current state on disk,
it will now set the CE_FSMONITOR_VALID bit.
Inversely, anytime git changes a cache entry, the CE_FSMONITOR_VALID bit
is cleared and the corresponding untracked cache directory is marked
invalid.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
By default, the preload index code path doesn't run unless there is a
minimum of 1000 files. To enable running the test suite and having it
execute the preload-index path, add an environment variable
(GIT_FORCE_PRELOAD_TEST) which will override that minimum and set it to 2.
This enables you run existing tests and have the core.preloadindex code
path execute as long as the test has at least 2 files by setting
GIT_FORCE_PRELOAD_TEXT=1 before running the test.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Teach preload-index to avoid lstat() calls for index-entries
with skip-worktree bit set. This is a performance optimization.
During a sparse-checkout, the skip-worktree bit is set on items
that were not populated and therefore are not present in the
worktree. The per-thread preload-index loop performs a series
of tests on each index-entry as it attempts to compare the
worktree version with the index and mark them up-to-date.
This patch short-cuts that work.
On a Windows 10 system with a very large repo (450MB index)
and various levels of sparseness, performance was improved
in the {preloadindex=true, fscache=false} case by 80% and
in the {preloadindex=true, fscache=true} case by 20% for various
commands.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Rename cache_def_free to cache_def_clear as it doesn't free the struct
cache_def, but just clears its content.
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
'git checkout' fails if a directory is longer than PATH_MAX, because the
lstat_cache in symlinks.c checks if the leading directory exists using
PATH_MAX-bounded string operations.
Remove the limitation by using strbuf instead.
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This helps reduce the number of match_pathspec_depth() call sites and
show how match_pathspec_depth() is used.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The rule has always been that a cache entry that is ce_uptodate(ce)
means that we already have checked the work tree entity and we know
there is no change in the work tree compared to the index, and nobody
should have to double check. Note that false ce_uptodate(ce) does not
mean it is known to be dirty---it only means we don't know if it is
clean.
There are a few codepaths (refresh-index and preload-index are among
them) that mark a cache entry as up-to-date based solely on the return
value from ie_match_stat(); this function uses lstat() to see if the
work tree entity has been touched, and for a submodule entry, if its
HEAD points at the same commit as the commit recorded in the index of
the superproject (a submodule that is not even cloned is considered
clean).
A submodule is no longer considered unmodified merely because its HEAD
matches the index of the superproject these days, in order to prevent
people from forgetting to commit in the submodule and updating the
superproject index with the new submodule commit, before commiting the
state in the superproject. However, the patch to do so didn't update
the codepath that marks cache entries up-to-date based on the updated
definition and instead worked it around by saying "we don't trust the
return value of ce_uptodate() for submodules."
This makes ce_uptodate() trustworthy again by not marking submodule
entries up-to-date.
The next step _could_ be to introduce a few "in-core" flag bits to
cache_entry structure to record "this entry is _known_ to be dirty",
call is_submodule_modified() from ie_match_stat(), and use these new
bits to avoid running this rather expensive check more than once, but
that can be a separate patch.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This uses the new thread-safe 'threaded_has_symlink_leading_path()'
function to efficiently verify that the whole path leading up to the
filename is a proper path, and does not contain symlinks.
This makes 'ce_uptodate()' a much stronger guarantee: it no longer just
guarantees that the 'lstat()' of the path would match, it also means
that we know that people haven't played games with moving directories
around and covered it up with symlinks.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This introduces make variable NO_PTHREADS for platforms that lack the
support for pthreads library or people who do not want to use it for
whatever reason. When defined, it makes the multi-threaded index
preloading into a no-op, and also disables threaded delta searching by
pack-objects.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Mike Ralphson <mike@abacus.co.uk>
Tested-by: Johannes Sixt <j6t@kdbg.org> (AIX 4.3.x)
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the threaded index preloading case, we must be sure to always use the
CE_MATCH_RACY_IS_DIRTY flag when calling ie_match_stat(), in order to make
sure that we only ever look at the stat() data, and don't try to do
anything fancy.
Because most of git internals are not thread-safe, and must not be called
in parallel.
Otherwise, what happens is that if the timestamps indicate that an entry
_might_ be dirty, we might start actually comparing filesystem data with
the object database. And we mustn't do that, because that would involve
looking up and creating the object structure, and that whole code sequence
with read_sha1_file() where we look up and add objects to the hashes is
definitely not thread-safe.
Nor do we want to add locking, because the whole point of the preload was
to be simple and not affect anything else. With CE_MATCH_RACY_IS_DIRTY, we
get what we wanted, and we'll just leave the hard cases well alone, to be
done later in the much simpler serial case.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This can do the lstat() storm in parallel, giving potentially much
improved performance for cold-cache cases or things like NFS that have
weak metadata caching.
Just use "read_cache_preload()" instead of "read_cache()" to force an
optimistic preload of the index stat data. The function takes a
pathspec as its argument, allowing us to preload only the relevant
portion of the index.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Junio C Hamano
Nguyễn Thái Ngọc Duy
Ben Peart
Jeff Hostetler
Karsten Blees
Pierre Habouzit
Linus Torvalds