@matheusbsbs / matheus-bagliano / commits / d79d299352

Accelerate clear_skip_worktree_from_present_files() by caching

Trying to clear the skip-worktree bit from files that are present does present some computational overhead, for sparse-checkouts. (We do not do the bit clearing in non-sparse-checkouts.) Optimize it as follows: Rather than lstat()'ing every SKIP_WORKTREE path, take advantage of the fact that entire directories will often be missing, especially for cone mode and even more so ever since commit 55dfcf9591 ("sparse-checkout: clear tracked sparse dirs", 2021-09-08). If we have already determined that the parent directory of a file (or other previous ancestor) does not exist, then the file cannot exist either so we do not need to lstat() it separately. Timings for p2000 included below, reformatted to fit in normal commit message line lengths, which compare three things: * Timings before this series * Timings of the unoptimized version of clear_skip_worktree_from_present_files() from a few commits ago * Timings after the optimization in this commit (NOTE: t/perf/ appears to have timing resolution only down to 0.01 s, which presents significant measurement error when timings only differ by 0.01s. I don't trust any such timings below, and yet all the optimized results differ by at most 0.01s.) Test Before Series Unoptimized Optimized ----------------------------------------------------------------------------- *git status* full-v3 0.15(0.10+0.06) 0.32(0.16+0.17) +113.3% 0.16(0.10+0.07) +6.7% full-v4 0.15(0.11+0.05) 0.32(0.17+0.16) +113.3% 0.16(0.11+0.05) +6.7% sparse-v3 0.04(0.03+0.04) 0.04(0.02+0.05) +0.0% 0.04(0.02+0.05) +0.0% sparse-v4 0.04(0.03+0.04) 0.04(0.02+0.05) +0.0% 0.04(0.03+0.05) +0.0% *git add -A* full-v3 0.40(0.30+0.07) 0.56(0.36+0.17) +40.0% 0.39(0.30+0.07) -2.5% full-v4 0.37(0.28+0.07) 0.54(0.37+0.16) +45.9% 0.38(0.29+0.07) +2.7% sparse-v3 0.06(0.04+0.05) 0.08(0.05+0.05) +33.3% 0.06(0.05+0.04) +0.0% sparse-v4 0.05(0.03+0.05) 0.05(0.04+0.04) +0.0% 0.06(0.04+0.05) +20.0% *git add .* full-v3 0.40(0.31+0.07) 0.57(0.37+0.17) +42.5% 0.41(0.30+0.08) +2.5% full-v4 0.38(0.30+0.06) 0.55(0.37+0.16) +44.7% 0.38(0.30+0.06) +0.0% sparse-v3 0.06(0.04+0.05) 0.06(0.05+0.04) +0.0% 0.06(0.03+0.05) +0.0% sparse-v4 0.06(0.05+0.05) 0.06(0.04+0.05) +0.0% 0.06(0.04+0.06) +0.0% *git commit -a -m A* full-v3 0.41(0.32+0.06) 0.58(0.39+0.17) +41.5% 0.42(0.32+0.07) +2.4% full-v4 0.39(0.30+0.07) 0.56(0.38+0.17) +43.6% 0.40(0.31+0.07) +2.6% sparse-v3 0.04(0.03+0.04) 0.04(0.03+0.04) +0.0% 0.04(0.03+0.04) +0.0% sparse-v4 0.04(0.03+0.05) 0.04(0.03+0.05) +0.0% 0.04(0.03+0.04) +0.0% *git checkout -f -* full-v3 0.56(0.46+0.07) 0.73(0.55+0.16) +30.4% 0.57(0.47+0.08) +1.8% full-v4 0.54(0.45+0.07) 0.71(0.53+0.17) +31.5% 0.55(0.45+0.07) +1.9% sparse-v3 0.06(0.04+0.04) 0.06(0.04+0.05) +0.0% 0.06(0.04+0.05) +0.0% sparse-v4 0.05(0.05+0.04) 0.05(0.04+0.05) +0.0% 0.06(0.04+0.05) +20.0% *git reset* full-v3 0.34(0.26+0.05) 0.51(0.34+0.15) +50.0% 0.34(0.26+0.06) +0.0% full-v4 0.32(0.24+0.06) 0.49(0.32+0.15) +53.1% 0.33(0.25+0.06) +3.1% sparse-v3 0.04(0.03+0.04) 0.04(0.03+0.04) +0.0% 0.04(0.03+0.04) +0.0% sparse-v4 0.03(0.03+0.04) 0.03(0.02+0.04) +0.0% 0.03(0.03+0.04) +0.0% *git reset --hard* full-v3 0.57(0.46+0.07) 0.90(0.61+0.25) +57.9% 0.57(0.45+0.08) +0.0% full-v4 0.54(0.46+0.05) 0.88(0.59+0.26) +63.0% 0.55(0.45+0.07) +1.9% sparse-v3 0.07(0.03+0.03) 0.07(0.04+0.03) +0.0% 0.07(0.03+0.03) +0.0% sparse-v4 0.06(0.03+0.03) 0.06(0.04+0.02) +0.0% 0.06(0.03+0.03) +0.0% *git reset -- does-not-exist* full-v3 0.35(0.27+0.06) 0.52(0.32+0.17) +48.6% 0.35(0.27+0.06) +0.0% full-v4 0.33(0.26+0.05) 0.50(0.33+0.15) +51.5% 0.33(0.26+0.06) +0.0% sparse-v3 0.04(0.03+0.04) 0.04(0.03+0.04) +0.0% 0.04(0.03+0.04) +0.0% sparse-v4 0.04(0.02+0.04) 0.03(0.02+0.04) -25.0% 0.03(0.02+0.04) -25.0% *git diff* full-v3 0.07(0.04+0.04) 0.24(0.11+0.14) +242.9% 0.07(0.04+0.04) +0.0% full-v4 0.07(0.03+0.05) 0.24(0.13+0.12) +242.9% 0.08(0.04+0.05) +14.3% sparse-v3 0.02(0.01+0.04) 0.02(0.01+0.04) +0.0% 0.02(0.01+0.05) +0.0% sparse-v4 0.02(0.02+0.03) 0.02(0.01+0.04) +0.0% 0.02(0.01+0.04) +0.0% *git diff --cached* full-v3 0.05(0.03+0.02) 0.22(0.12+0.09) +340.0% 0.05(0.03+0.01) +0.0% full-v4 0.05(0.03+0.01) 0.23(0.12+0.11) +360.0% 0.05(0.03+0.02) +0.0% sparse-v3 0.01(0.00+0.00) 0.01(0.00+0.00) +0.0% 0.01(0.00+0.00) +0.0% sparse-v4 0.01(0.00+0.00) 0.01(0.00+0.00) +0.0% 0.01(0.00+0.00) +0.0% *git blame f2/f4/a* full-v3 0.18(0.13+0.05) 0.52(0.29+0.23) +188.9% 0.19(0.15+0.04) +5.6% full-v4 0.19(0.15+0.04) 0.52(0.28+0.23) +173.7% 0.19(0.14+0.04) +0.0% sparse-v3 0.10(0.08+0.02) 0.10(0.09+0.01) +0.0% 0.10(0.09+0.01) +0.0% sparse-v4 0.10(0.08+0.02) 0.10(0.08+0.02) +0.0% 0.10(0.08+0.02) +0.0% *git blame f2/f4/f3/a* full-v3 0.45(0.36+0.08) 0.78(0.51+0.27) +73.3% 0.45(0.37+0.08) +0.0% full-v4 0.45(0.37+0.08) 0.78(0.51+0.26) +73.3% 0.45(0.37+0.08) +0.0% sparse-v3 0.36(0.32+0.04) 0.36(0.31+0.05) +0.0% 0.36(0.31+0.04) +0.0% sparse-v4 0.36(0.31+0.05) 0.36(0.31+0.05) +0.0% 0.36(0.31+0.04) +0.0% *git checkout-index -f --all* full-v3 0.07(0.02+0.05) 0.24(0.12+0.12) +242.9% 0.08(0.04+0.04) +14.3% full-v4 0.07(0.03+0.04) 0.24(0.11+0.13) +242.9% 0.08(0.03+0.04) +14.3% sparse-v3 0.04(0.01+0.03) 0.04(0.00+0.03) +0.0% 0.04(0.01+0.03) +0.0% sparse-v4 0.04(0.01+0.02) 0.04(0.01+0.03) +0.0% 0.04(0.01+0.02) +0.0% *git update-index --add --remove f2/f4/a* full-v3 0.29(0.23+0.02) 0.46(0.30+0.12) +58.6% 0.30(0.24+0.02) +3.4% full-v4 0.27(0.22+0.02) 0.45(0.29+0.12) +66.7% 0.28(0.22+0.03) +3.7% sparse-v3 0.02(0.02+0.00) 0.02(0.01+0.00) +0.0% 0.02(0.01+0.00) +0.0% sparse-v4 0.02(0.02+0.00) 0.02(0.02+0.00) +0.0% 0.02(0.02+0.00) +0.0% So, with the optimization, the extra work appears to be essentially 0 for sparse-checkouts that are also using sparse-indexes (even before my optimization), and the extra work appears to be just marginally more than 0 for sparse-checkouts that are using full indexes. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Elijah Newren committed Jan 14, 2022 at 15:59 UTC d79d29935262f8422a6e620bd33cc2fce28e669d
1 file changed +54 -2
sparse-index.c
+54 -2
@@ -341,18 +341,70 @@ void ensure_correct_sparsity(struct index_state *istate)
341 ensure_full_index(istate);
342 }
343
344 +static int path_found(const char *path, const char **dirname, size_t *dir_len,
345 + int *dir_found)
346 +{
347 + struct stat st;
348 + char *newdir;
349 + char *tmp;
350 +
351 + /*
352 + * If dirname corresponds to a directory that doesn't exist, and this
353 + * path starts with dirname, then path can't exist.
354 + */
355 + if (!*dir_found && !memcmp(path, *dirname, *dir_len))
356 + return 0;
357 +
358 + /*
359 + * If path itself exists, return 1.
360 + */
361 + if (!lstat(path, &st))
362 + return 1;
363 +
364 + /*
365 + * Otherwise, path does not exist so we'll return 0...but we'll first
366 + * determine some info about its parent directory so we can avoid
367 + * lstat calls for future cache entries.
368 + */
369 + newdir = strrchr(path, '/');
370 + if (!newdir)
371 + return 0; /* Didn't find a parent dir; just return 0 now. */
372 +
373 + /*
374 + * If path starts with directory (which we already lstat'ed and found),
375 + * then no need to lstat parent directory again.
376 + */
377 + if (*dir_found && *dirname && memcmp(path, *dirname, *dir_len))
378 + return 0;
379 +
380 + /* Free previous dirname, and cache path's dirname */
381 + *dirname = path;
382 + *dir_len = newdir - path + 1;
383 +
384 + tmp = xstrndup(path, *dir_len);
385 + *dir_found = !lstat(tmp, &st);
386 + free(tmp);
387 +
388 + return 0;
389 +}
390 +
391 void clear_skip_worktree_from_present_files(struct index_state *istate)
392 {
393 + const char *last_dirname = NULL;
394 + size_t dir_len = 0;
395 + int dir_found = 1;
396 +
397 int i;
398 +
399 if (!core_apply_sparse_checkout)
400 return;
401
402 restart:
403 for (i = 0; i < istate->cache_nr; i++) {
404 struct cache_entry *ce = istate->cache[i];
353 - struct stat st;
405
355 - if (ce_skip_worktree(ce) && !lstat(ce->name, &st)) {
406 + if (ce_skip_worktree(ce) &&
407 + path_found(ce->name, &last_dirname, &dir_len, &dir_found)) {
408 if (S_ISSPARSEDIR(ce->ce_mode)) {
409 ensure_full_index(istate);
410 goto restart;