file(1) command very slow

Eugene Grosbein eugen at grosbein.net
Sat Sep 5 11:39:05 UTC 2015


05.09.2015 15:53, Martin Birgmeier пишет:
> Running the file(1) command on a 7 MB text file takes much longer in
> 10.2 than in 10.1.
>
> Example:
>
> # ll /tmp/x6
> -rw-r--r--  1 root  wheel  7384414 Sep  5 10:30 /tmp/x6
> # file /tmp/x6
> /tmp/x6: ASCII text
> file /tmp/x6  26.12s user 0.00s system 99% cpu 26.237 total
> #
>
> I have this on all my machines since installing 10.2.
>
> Any ideas on what is wrong?

That's performance regression in the file-5.23 compared with file-5.22
bundled with earlier versions of FreeBSD.

I have reported it upstream about 3 weeks ago but got no response:
http://bugs.gw.com/view.php?id=474

For me, 5.23 is 130+ times slower than 5.22.
Partially that's because of larger look-ahead buffer (1MB vs. 256K):
https://github.com/file/file/commit/dd89d293fe62ca55542a5637e239b33404c58a8d

However, backout of this change gets only 10 times speedup, not 130 times,
so there should be more changes guilty.

Eugene Grosbein



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