That is a fun exercise, but I imagine the time to evaluate the conditional expression is a tiny fraction, just a percent or less, than the time it takes to make the file system calls.

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nasretdinov 9 hours ago | parent | next [-]

For many cases you don't even need to make stat() call to determine whether or not the file is a directory (d_type specifically can tell it: https://man7.org/linux/man-pages/man3/readdir.3.html). That's what allows find(1) to be so quick

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loeg 6 hours ago | parent [-]

You could imagine determining from the parsed expression whether or not stat'ing was required.

NFS has readdirplus, but I don't think it ever made its way into Linux/POSIX. (Some filesystems could efficiently return dirents + stat information.)

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nasretdinov 5 hours ago | parent [-]

> readdirplus

Well, it definitely does _something_, because on NFS the subsequent stat() calls after reading the directory names do indeed complete instantly :), at least in my testing.

	▲	loeg 5 hours ago \| parent [-]
		I mean, readdirplus as a local filesystem API. Ultimately unix programs are just invoking getdents() (or equivalent) + stat() (or statx, whatever). Linux nfsclient probably caches the result of readdirplus for subsequent stat.

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CerryuDu 9 hours ago | parent | prev [-]

... not to mention the time it takes to load directory entries and inodes when the cache is cold.