$ ptime /usr/gnu/bin/grep mysqld 1_4GB_txt_file
real 1:32.055472017
user 1:30.202692546
sys 0.907308690
$ ptime /usr/bin/grep mysqld
real 8.725173958
user 7.621411130
sys 1.056151347
I guess it's due to GNU version being compiled without optimizations... or maybe it is something else. Once I find some time I will try to investigate it.
3 comments:
is gnu grep actually trying to do case insensitive searches or searching in multiple character sets?
That usually explains such slowdowns.
GNU grep is slow in UTF-8 locales, I've heard. What happens if you set LC_ALL=C?
Bingo! With LC_ALL=C GNU grep finished in less than 2s while it didn't make any difference for the other grep. Partly it could be due to the fact that GNU grep uses 32KB buffer for reading compared to 8KB... but there's probably more to it.
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