[illumos-Developer] webrev: 650 grep support for -q would be useful

[Yuri Pankov]

On Tue, May 03, 2011 at 08:47:26PM +0400, Yuri Pankov wrote:
> ----------------------------------------------------------------
> Bad performance when given a lot of files:
> ----------------------------------------------------------------
> GNU grep:
> $ time for i in `seq 1 100`; do /usr/gnu/bin/grep -q switch \
>   ~/src/illumos/illumos-gate/usr/src/uts/common/io/*; done
> 
> real    0m2.621s
> user    0m1.773s
> sys     0m0.841s
> 
> BSD grep:
> $ time for i in `seq 1 100`; do ~/ws/650-grep-q/usr/src/cmd/grep/grep -q \
>   switch ~/src/illumos/illumos-gate/usr/src/uts/common/io/*; done
> 
> real    0m11.620s
> user    0m7.491s
> sys     0m4.176s
> ----------------------------------------------------------------
> 
> ----------------------------------------------------------------
> Same (actually much worse) for -R/-r:
> ----------------------------------------------------------------
> GNU grep:
> $ time for i in `seq 1 100`; do /usr/gnu/bin/grep -rq switch \
>   ~/src/illumos/illumos-gate/usr/src/uts/common/io/; done
> 
> real    0m0.870s
> user    0m0.209s
> sys     0m0.642s
> 
> BSD grep:
> $ time for i in `seq 1 100`; do ~/ws/650-grep-q/usr/src/cmd/grep/grep
> -rq switch ~/src/illumos/illumos-gate/usr/src/uts/common/io/; done
> 
> real    2m34.742s
> user    1m48.919s
> sys     0m45.556s
> ----------------------------------------------------------------

INCORRECT. GNU grep seems to cheat when given -q (BSD grep could do the
same though):

----------------------------------------------------------------
Lot of files:
----------------------------------------------------------------
GNU grep:
$ time for i in `seq 1 100`; do /usr/gnu/bin/grep switch \
  ~/src/illumos/illumos-gate/usr/src/uts/common/io/* > /dev/null; done

real    0m37.744s
user    0m33.017s
sys     0m4.656s

BSD grep:
$ time for i in `seq 1 100`; do ~/ws/650-grep-q/usr/src/cmd/grep/grep \
  switch ~/src/illumos/illumos-gate/usr/src/uts/common/io/* > /dev/null; \
  done

real    0m19.577s
user    0m14.601s
sys     0m5.252s
----------------------------------------------------------------

----------------------------------------------------------------
Recursive:
----------------------------------------------------------------
GNU grep:
$ time for i in `seq 1 100`; do /usr/gnu/bin/grep -r switch \
  ~/src/illumos/illumos-gate/usr/src/uts/common/io/ > gnugrep.out; done

real    11m19.720s
user    9m46.833s
sys     1m31.770s

$ time for i in `seq 1 100`; do ~/ws/650-grep-q/usr/src/cmd/grep/grep -r \
  switch ~/src/illumos/illumos-gate/usr/src/uts/common/io/ > bsdgrep.out; \
  done

real    4m18.712s
user    3m9.223s
sys     1m8.911s
----------------------------------------------------------------

This looks much better...


Yuri