Re: directories to check?

[Torsten Mohr]

You're right, i assumed that doing all the necessary stat()s
at once saves time.  If this is not the case, it won't save time.

To do some more profiling i think i'll need to compile some test
versions of "make" with debug output.  This will be the next step.


Best regards,
Torsten.



> %% Torsten Mohr <address@hidden> writes:
>
>   tm> I still think this may be a good idea to speed things up:
>   >> > Make could then first read all the hint-directory contents and
>   >> > their timestamps and then use these informations as a "cache".
>   >> >
>   >> >
>   >> > Would that be possible?
>   >> >
>   >> > Would that be an improvement?
>   >> >
>   >> > Is something like this maybe already available and i just haven't
>   >> > yet seen it?
>
>   tm> Is the effort to implement this big?  Is it a major architecture
>   tm> change?
>
> I guess I don't really understand your suggestion.
>
> There's no UNIX operation to "bulk retrieve" stat information about a
> whole directory of files, that is "extra fast" or something.  Regardless
> of whether you do it early or late, you're going to be running stat on
> the same number of files (actually, maybe even more files with your
> method as you'll stat the whole directory even though make might end up
> caring about only a few files in it).  It will take the same amount of
> time.
>
> Also, note that GNU make already does cache directories and stat info to
> the extent that it's possible to do so without impacting its
> functionality... in fact there are a number of bug reports that this
> caching causes some makefiles that work properly in other versions of
> make to not work as expected with GNU make.
>
>
> I'm frankly skeptical that the "startup time" you refer to has anything
> at all to do with this.  Have you done any profiling of the make process
> to see where it's spending all of its time?
>
> Note that some kinds of string operations, in some situations, can be
> very inefficient.  Some of these things were worked on a bit in the
> current beta release; give this a whirl:
>
>     ftp://alpha.gnu.org/gnu/make/make-3.81beta3.tar.gz
>
> and see if it's any better.  If not you'll need to do some profiling.