Re: WC modification detection is reading whole files

On Tuesday 21 February 2006 00:26, Branko Čibej wrote:
> >> These are in both cases repeatable times, when all the files are in the
> >> OS's disk cache so the disk activity light doesn't even flicker.
> >
> > How about storing an MD5 of, say, every 64kB of the translated file?
> > Then a comparision wouldn't need to compare N bytes to N bytes (with
> > approx. 2*N/2 read on average),
>
> Did you count the cost of computing the MD5?
As long as in cache:
        $ ls -la /usr/bin/blender-bin
        -rwxr-xr-x 1 root root 7336064 2006-02-07 12:43 /usr/bin/blender-bin
        $ time md5sum /usr/bin/blender-bin
        acd4c030ec56a84003e904adad9a8cd0 /usr/bin/blender-bin

        real 0m0.064s
        user 0m0.047s
        sys 0m0.009s

on a P4 1.7GHz ... makes no time difference.
If it's not in cache ... harddisk is slower.

Regards,

Phil

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Received on Tue Feb 21 11:13:25 2006