Official request: Please make GNU grep the default

[Alan Cox]

On Tue, Aug 17, 2010 at 3:29 PM, Dimitry Andric <dimitry at andric.com> wrote:

> On 2010-08-17 18:29, Alan Cox wrote:
> > Try it again on a memory resident file with the MAP_PREFAULT_READ option
> > that is provided by this patch:
> >
> > http://www.cs.rice.edu/~alc/MAP_PREFAULT_READ.patch<http://www.cs.rice.edu/%7Ealc/MAP_PREFAULT_READ.patch>
>
> A time trial gives:
>
>  grep with normal mmap()       1396s
>  grep with prefault mmap()     1354s
>  grep with regular read()      1354s
>
> 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?  Does
the value of "sysctl vm.pmap.pde.mappings" increase as a result of your
test?  If not, there is still room for improvement in the results with
mmap().

Alan