Re: Improvement on parallel make

[Alexey Neyman]

Philip,

It is ok if there is a clear dependency like you pointed out.

There may be cases when it doesn't work, however. E.g. the 'ar' tool 
does not lock the archive while updating it. Thus, running 'ar' on 
the same archive concurrently may corrupt it.

Imagine that both local Makefile and Makefiles in subdirectories need 
to update the archive. How do you express it using normal 
dependencies?

Regards,
Alexey.

On Tuesday 12 December 2006 11:23, Philip Guenther wrote:
> [Dang it, fingers slipped and I sent while still editting.  So to 
continue...]
> 
> Note that the desired makefile mentioned above:
>   local_objects = a.o b.o c.o d.o
>   all: all-recursive .WAIT all-local
>   all-recursive:
>        $(MAKE) -C subdir all
>   all-local: $(local_objects)
> 
> can *currently* be implemented like this:
> 
>   local_objects = a.o b.o c.o d.o
>   all: all-recursive
>       $(MAKE) all-local
>   all-recursive:
>       $(MAKE) -C subdir all
>   all-local: $(local_objects)
> 
> The choice to use recursive make means you've given up on maximizing
> your parallelism (because your dependency tree has to be a superset 
of
> the real tree).  As long as you've burned that bridge, why not use 
it
> here to express the ordering?
> 
> 
> Philip Guenther
> 
> 
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> 

-- 
Your efforts are valid, merely incomplete.
                        -- Supox, SC2