Re: Official request: Please make GNU grep the default

On Thursday, August 19, 2010 10:12:11 am Dimitry Andric wrote:
> On 2010-08-17 23:24, Alan Cox wrote:
> >> So normal mmap is ~3% slower, and prefault mmap does not seem to make
> >> any measurable difference.  I guess the added complexity is not really
> >> worth it, for now.
> > 
> > Do you know what fraction of this time is being spent in the kernel?
> 
> I ran 100 trials again, but now using "time -a -o logfile", so I could
> run ministat over the accumulated results.  This gives:
> 
> x gnugrep
> + bsdgrep-r210927 (the initial version that started this thread)
> * bsdgrep-r211490 (current version)
> % bsdgrep-r211490-mmap-plain
> # bsdgrep-r211490-mmap-prefault
> 
> Real time:
>     N           Min           Max        Median           Avg        Stddev
> x 100          1.15          1.98          1.18        1.2122    0.11159613
> + 100          8.57         14.26          8.79        9.1823     1.0496126
> * 100          2.81          6.57          2.91        3.0189     0.4304259
> % 100          2.34          4.03          2.99        3.0022    0.12635992
> # 100          2.85          3.49          2.88        2.8981   0.075232904
> 
> User time:
>     N           Min           Max        Median           Avg        Stddev
> x 100             0          0.07          0.03        0.0239   0.015627934
> + 100           1.6          3.33           1.9         1.976    0.30264824
> * 100          0.29             1          0.39        0.4004    0.08696824
> % 100           1.8          3.56          2.73        2.7274    0.13260117
> # 100          2.78          3.04          2.81        2.8238    0.04039652
> 
> System time:
>     N           Min           Max        Median           Avg        Stddev
> x 100          1.08          1.91          1.15        1.1809    0.10953617
> + 100          6.55          10.9          6.94        7.1905    0.77911809
> * 100          2.38           5.5          2.53        2.6061    0.35068445
> % 100          0.18          0.53          0.25        0.2645   0.053586049
> # 100          0.03          0.54          0.06        0.0668   0.052259647
> 
> E.g. it looks like bsdgrep with 'plain' mmap performs almost the same
> as the regular bsdgrep (both around 3.0s average), but with mmap much
> more of the time is spent in user mode.

I would add user and system time together and compare the total time.  Given 
that statclock only fires at 128 hz, and we use those counts to subdivide 
rux_runtime, I don't put much faith in user vs system time for benchmarks, 
only the total runtime in rux_runtime (which is user + system) is truly 
accurate.

-- 
John Baldwin