[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: fgrep execution time

From: David Bailey
Subject: Re: fgrep execution time
Date: Wed, 23 Feb 2005 09:34:03 +0900


Very impressive! Thanks for the tip. 

> GNU grep 2.5.1 is awfully inefficient with non-C locales.
> How would the times look like if you tried the following?
> time yes "a very long file" | \
>     head -10000 | LC_ALL=C /usr/local/bin/fgrep -f /dev/null

Looks like the locale setting caused the problem.

When we set LC_ALL=C, the run times were similar to /bin/fgrep and 
/usr/xpg4/bin/grep -F.

prompt> setenv LANG ja
prompt> time yes "a very big file" | \
        head -100000 | /usr/local/bin/grep -f /dev/null
0.0u 0.0s 1:15 0% 0+0k 0+0io 0pf+0w

prompt> setenv LANG C
prompt> time yes "a very big file" | \
        head -100000 | /usr/local/bin/grep -f /dev/null
0.0u 0.0s 0:00 0% 0+0k 0+0io 0pf+0w

The third field in the output of the csh time command is wallclock time.

75 seconds when locale is ja (Japanese), less then 1 second when locale
is C.

BTW: We get the same results under Linux (RedHat EL 3.0 AS).

David M. Bailey

Attachment: bailey-david.vcf
Description: David Bailey ĚJ[h

reply via email to

[Prev in Thread] Current Thread [Next in Thread]