From 65a7814b2dbc10ea86610092f03d0c1df95d08ad Mon Sep 17 00:00:00 2001 From: Tavian Barnes Date: Thu, 23 May 2024 14:28:02 -0400 Subject: opt: Don't raise RLIMIT_NOFILE if it would prevent using posix_spawn() If we raise RLIMIT_NOFILE, we have to lower it before calling exec() for compatibility with select(). If posix_spawn() doesn't support that, we fall back to fork(), which is quite a bit slower. Therefore, if we're going to exec() on most files, it's better to keep RLIMIT_NOFILE the same to avoid the fork() cost, even though it makes bftw() somewhat slower. --- src/opt.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'src/opt.c') diff --git a/src/opt.c b/src/opt.c index d1dee11..6704a46 100644 --- a/src/opt.c +++ b/src/opt.c @@ -2221,6 +2221,11 @@ static float estimate_stat_odds(struct bfs_ctx *ctx) { return 1.0 - nostat_odds; } +/** Matches -(exec|ok) ... \; */ +static bool single_exec(const struct bfs_expr *expr) { + return expr->eval_fn == eval_exec && !(expr->exec->flags & BFS_EXEC_MULTI); +} + int bfs_optimize(struct bfs_ctx *ctx) { bfs_ctx_dump(ctx, DEBUG_OPT); @@ -2299,6 +2304,17 @@ int bfs_optimize(struct bfs_ctx *ctx) { opt_leave(&opt, "eager stat cost: ${ylw}%g${rs}\n", eager_cost); } +#ifndef POSIX_SPAWN_SETRLIMIT + // If bfs_spawn_setrlimit() would force us to use fork() over + // posix_spawn(), the extra cost may outweigh the benefit of a + // higher RLIMIT_NOFILE + float single_exec_odds = estimate_odds(ctx->expr, single_exec); + if (single_exec_odds >= 0.5) { + opt_enter(&opt, "single ${blu}-exec${rs} odds: ${ylw}%g${rs}\n", single_exec_odds); + ctx->raise_nofile = false; + opt_leave(&opt, "not raising RLIMIT_NOFILE\n"); + } +#endif } opt_leave(&opt, NULL); -- cgit v1.2.3