[PATCH 1/7] diffcore-rename: use a mem_pool for exact rename detection's hashmap
From: Elijah Newren via GitGitGadget <hidden>
Date: 2021-07-23 12:55:04
Subsystem:
the rest · Maintainer:
Linus Torvalds
From: Elijah Newren <redacted>
Exact rename detection, via insert_file_table(), uses a hashmap to store
files by oid. Use a mem_pool for the hashmap entries so these can all be
allocated and deallocated together.
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: 204.2 ms ± 3.0 ms 202.5 ms ± 3.2 ms
mega-renames: 1.076 s ± 0.015 s 1.072 s ± 0.012 s
just-one-mega: 364.1 ms ± 7.0 ms 357.3 ms ± 3.9 ms
Signed-off-by: Elijah Newren <redacted>
---
diffcore-rename.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/diffcore-rename.c b/diffcore-rename.c
index 4ef0459cfb5..23b917eca42 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c@@ -317,10 +317,11 @@ static int find_identical_files(struct hashmap *srcs, } static void insert_file_table(struct repository *r, + struct mem_pool *pool, struct hashmap *table, int index, struct diff_filespec *filespec) { - struct file_similarity *entry = xmalloc(sizeof(*entry)); + struct file_similarity *entry = mem_pool_alloc(pool, sizeof(*entry)); entry->index = index; entry->filespec = filespec;
@@ -336,7 +337,8 @@ static void insert_file_table(struct repository *r, * and then during the second round we try to match * cache-dirty entries as well. */ -static int find_exact_renames(struct diff_options *options) +static int find_exact_renames(struct diff_options *options, + struct mem_pool *pool) { int i, renames = 0; struct hashmap file_table;
@@ -346,7 +348,7 @@ static int find_exact_renames(struct diff_options *options) */ hashmap_init(&file_table, NULL, NULL, rename_src_nr); for (i = rename_src_nr-1; i >= 0; i--) - insert_file_table(options->repo, + insert_file_table(options->repo, pool, &file_table, i, rename_src[i].p->one);
@@ -355,7 +357,7 @@ static int find_exact_renames(struct diff_options *options) renames += find_identical_files(&file_table, i, options); /* Free the hash data structure and entries */ - hashmap_clear_and_free(&file_table, struct file_similarity, entry); + hashmap_clear(&file_table); return renames; }
@@ -1341,6 +1343,7 @@ void diffcore_rename_extended(struct diff_options *options, int num_destinations, dst_cnt; int num_sources, want_copies; struct progress *progress = NULL; + struct mem_pool local_pool; struct dir_rename_info info; struct diff_populate_filespec_options dpf_options = { .check_binary = 0,
@@ -1409,11 +1412,18 @@ void diffcore_rename_extended(struct diff_options *options, goto cleanup; /* nothing to do */ trace2_region_enter("diff", "exact renames", options->repo); + mem_pool_init(&local_pool, 32*1024); /* * We really want to cull the candidates list early * with cheap tests in order to avoid doing deltas. */ - rename_count = find_exact_renames(options); + rename_count = find_exact_renames(options, &local_pool); + /* + * Discard local_pool immediately instead of at "cleanup:" in order + * to reduce maximum memory usage; inexact rename detection uses up + * a fair amount of memory, and mem_pools can too. + */ + mem_pool_discard(&local_pool, 0); trace2_region_leave("diff", "exact renames", options->repo); /* Did we only want exact renames? */
--
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