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From: "Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: "Derrick Stolee" <dstolee@microsoft.com>,
	"Jonathan Tan" <jonathantanmy@google.com>,
	"Taylor Blau" <me@ttaylorr.com>,
	"Junio C Hamano" <gitster@pobox.com>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Elijah Newren" <newren@gmail.com>,
	"Elijah Newren" <newren@gmail.com>,
	"Elijah Newren" <newren@gmail.com>
Subject: [PATCH v2 8/8] diffcore-rename: avoid doing basename comparisons for irrelevant sources
Date: Tue, 09 Mar 2021 00:09:59 +0000	[thread overview]
Message-ID: <c443ba8abb89458cf2b883d8777fb3f703a90ff9.1615248599.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.845.v2.git.1615248599.gitgitgadget@gmail.com>

From: Elijah Newren <newren@gmail.com>

The basename comparison optimization implemented in
find_basename_matches() is very beneficial since it allows a source to
sometimes only be compared with one other file instead of N other files.
When a match is found, both a source and destination can be removed from
the matrix of inexact rename comparisons.  In contrast, the irrelevant
source optimization only allows us to remove a source from the matrix of
inexact rename comparisons...but it has the advantage of allowing a
source file to not even be loaded into memory at all and be compared to
0 other files.  Generally, not even comparing is a bigger performance
win, so when both optimizations could apply, prefer to use the
irrelevant-source optimization.

For the testcases mentioned in commit 557ac0350d ("merge-ort: begin
performance work; instrument with trace2_region_* calls", 2020-10-28),
this change improves the performance as follows:

                            Before                  After
    no-renames:        5.708 s ±  0.111 s     5.680 s ±  0.096 s
    mega-renames:    102.171 s ±  0.440 s    13.812 s ±  0.162 s
    just-one-mega:     3.471 s ±  0.015 s   506.0  ms ±  3.9  ms

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 diffcore-rename.c | 37 +++++++++++++++++++++++++++++++++----
 1 file changed, 33 insertions(+), 4 deletions(-)

diff --git a/diffcore-rename.c b/diffcore-rename.c
index 7f6115fd9018..e8508541be14 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -527,6 +527,7 @@ static void update_dir_rename_counts(struct dir_rename_info *info,
 }
 
 static void initialize_dir_rename_info(struct dir_rename_info *info,
+				       struct strset *relevant_sources,
 				       struct strset *dirs_removed,
 				       struct strmap *dir_rename_count)
 {
@@ -534,7 +535,7 @@ static void initialize_dir_rename_info(struct dir_rename_info *info,
 	struct strmap_entry *entry;
 	int i;
 
-	if (!dirs_removed) {
+	if (!dirs_removed && !relevant_sources) {
 		info->setup = 0;
 		return;
 	}
@@ -549,7 +550,20 @@ static void initialize_dir_rename_info(struct dir_rename_info *info,
 	strmap_init_with_options(&info->dir_rename_guess, NULL, 0);
 
 	/* Setup info->relevant_source_dirs */
-	info->relevant_source_dirs = dirs_removed;
+	info->relevant_source_dirs = NULL;
+	if (dirs_removed || !relevant_sources) {
+		info->relevant_source_dirs = dirs_removed; /* might be NULL */
+	} else {
+		info->relevant_source_dirs = xmalloc(sizeof(struct strintmap));
+		strset_init(info->relevant_source_dirs);
+		strset_for_each_entry(relevant_sources, &iter, entry) {
+			char *dirname = get_dirname(entry->key);
+			if (!dirs_removed ||
+			    strset_contains(dirs_removed, dirname))
+				strset_add(info->relevant_source_dirs, dirname);
+			free(dirname);
+		}
+	}
 
 	/*
 	 * Loop setting up both info->idx_map, and doing setup of
@@ -627,6 +641,13 @@ static void cleanup_dir_rename_info(struct dir_rename_info *info,
 	/* dir_rename_guess */
 	strmap_clear(&info->dir_rename_guess, 1);
 
+	/* relevant_source_dirs */
+	if (info->relevant_source_dirs &&
+	    info->relevant_source_dirs != dirs_removed) {
+		strset_clear(info->relevant_source_dirs);
+		FREE_AND_NULL(info->relevant_source_dirs);
+	}
+
 	/* dir_rename_count */
 	if (!keep_dir_rename_count) {
 		partial_clear_dir_rename_count(info->dir_rename_count);
@@ -749,6 +770,7 @@ static int idx_possible_rename(char *filename, struct dir_rename_info *info)
 static int find_basename_matches(struct diff_options *options,
 				 int minimum_score,
 				 struct dir_rename_info *info,
+				 struct strset *relevant_sources,
 				 struct strset *dirs_removed)
 {
 	/*
@@ -839,6 +861,11 @@ static int find_basename_matches(struct diff_options *options,
 		intptr_t src_index;
 		intptr_t dst_index;
 
+		/* Skip irrelevant sources */
+		if (relevant_sources &&
+		    !strset_contains(relevant_sources, filename))
+			continue;
+
 		/*
 		 * If the basename is unique among remaining sources, then
 		 * src_index will equal 'i' and we can attempt to match it
@@ -1164,7 +1191,7 @@ void diffcore_rename_extended(struct diff_options *options,
 
 		/* Preparation for basename-driven matching. */
 		trace2_region_enter("diff", "dir rename setup", options->repo);
-		initialize_dir_rename_info(&info,
+		initialize_dir_rename_info(&info, relevant_sources,
 					   dirs_removed, dir_rename_count);
 		trace2_region_leave("diff", "dir rename setup", options->repo);
 
@@ -1172,7 +1199,9 @@ void diffcore_rename_extended(struct diff_options *options,
 		trace2_region_enter("diff", "basename matches", options->repo);
 		rename_count += find_basename_matches(options,
 						      min_basename_score,
-						      &info, dirs_removed);
+						      &info,
+						      relevant_sources,
+						      dirs_removed);
 		trace2_region_leave("diff", "basename matches", options->repo);
 
 		/*
-- 
gitgitgadget

  parent reply	other threads:[~2021-03-09  0:11 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-28  3:58 [PATCH 0/8] Optimization batch 9: avoid detecting irrelevant renames Elijah Newren via GitGitGadget
2021-02-28  3:58 ` [PATCH 1/8] diffcore-rename: enable filtering possible rename sources Elijah Newren via GitGitGadget
2021-02-28  3:58 ` [PATCH 2/8] merge-ort: precompute subset of sources for which we need rename detection Elijah Newren via GitGitGadget
2021-02-28  3:58 ` [PATCH 3/8] merge-ort: add data structures for an alternate tree traversal Elijah Newren via GitGitGadget
2021-02-28  3:58 ` [PATCH 4/8] merge-ort: introduce wrappers for " Elijah Newren via GitGitGadget
2021-02-28  3:58 ` [PATCH 5/8] merge-ort: precompute whether directory rename detection is needed Elijah Newren via GitGitGadget
2021-02-28  3:58 ` [PATCH 6/8] merge-ort: use relevant_sources to filter possible rename sources Elijah Newren via GitGitGadget
2021-02-28  3:58 ` [PATCH 7/8] merge-ort: skip rename detection entirely if possible Elijah Newren via GitGitGadget
2021-02-28  3:58 ` [PATCH 8/8] diffcore-rename: avoid doing basename comparisons for irrelevant sources Elijah Newren via GitGitGadget
2021-03-01 16:39 ` [PATCH 0/8] Optimization batch 9: avoid detecting irrelevant renames Elijah Newren
2021-03-04  7:54 ` Elijah Newren
2021-03-09  0:09 ` [PATCH v2 " Elijah Newren via GitGitGadget
2021-03-09  0:09   ` [PATCH v2 1/8] diffcore-rename: enable filtering possible rename sources Elijah Newren via GitGitGadget
2021-03-09 22:21     ` Derrick Stolee
2021-03-09 22:40       ` Elijah Newren
2021-03-09 22:45         ` Derrick Stolee
2021-03-09  0:09   ` [PATCH v2 2/8] merge-ort: precompute subset of sources for which we need rename detection Elijah Newren via GitGitGadget
2021-03-09  0:09   ` [PATCH v2 3/8] merge-ort: add data structures for an alternate tree traversal Elijah Newren via GitGitGadget
2021-03-09  0:09   ` [PATCH v2 4/8] merge-ort: introduce wrappers for " Elijah Newren via GitGitGadget
2021-03-09 23:06     ` Derrick Stolee
2021-03-09  0:09   ` [PATCH v2 5/8] merge-ort: precompute whether directory rename detection is needed Elijah Newren via GitGitGadget
2021-03-09  0:09   ` [PATCH v2 6/8] merge-ort: use relevant_sources to filter possible rename sources Elijah Newren via GitGitGadget
2021-03-09  0:09   ` [PATCH v2 7/8] merge-ort: skip rename detection entirely if possible Elijah Newren via GitGitGadget
2021-03-09 22:51     ` Derrick Stolee
2021-03-09 22:57       ` Elijah Newren
2021-03-09  0:09   ` Elijah Newren via GitGitGadget [this message]
2021-03-09 22:08   ` [PATCH v2 0/8] Optimization batch 9: avoid detecting irrelevant renames Derrick Stolee
2021-03-10 15:08   ` Derrick Stolee
2021-03-11  0:38   ` [PATCH v3 " Elijah Newren via GitGitGadget
2021-03-11  0:38     ` [PATCH v3 1/8] diffcore-rename: enable filtering possible rename sources Elijah Newren via GitGitGadget
2021-03-11  0:38     ` [PATCH v3 2/8] merge-ort: precompute subset of sources for which we need rename detection Elijah Newren via GitGitGadget
2021-03-11  0:38     ` [PATCH v3 3/8] merge-ort: add data structures for an alternate tree traversal Elijah Newren via GitGitGadget
2021-03-11  0:38     ` [PATCH v3 4/8] merge-ort: introduce wrappers for " Elijah Newren via GitGitGadget
2021-03-11  0:38     ` [PATCH v3 5/8] merge-ort: precompute whether directory rename detection is needed Elijah Newren via GitGitGadget
2021-03-11  0:38     ` [PATCH v3 6/8] merge-ort: use relevant_sources to filter possible rename sources Elijah Newren via GitGitGadget
2021-03-11  0:38     ` [PATCH v3 7/8] merge-ort: skip rename detection entirely if possible Elijah Newren via GitGitGadget
2021-03-11  0:38     ` [PATCH v3 8/8] diffcore-rename: avoid doing basename comparisons for irrelevant sources Elijah Newren via GitGitGadget
2021-03-15 13:57     ` [PATCH v3 0/8] Optimization batch 9: avoid detecting irrelevant renames Derrick Stolee
2021-03-15 17:10   ` [PATCH v2 " Elijah Newren

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