Re: Looking for speed increases in "make index" and pkg_version for ports

Stephen Montgomery-Smith wrote:
Hartmut Brandt wrote:

Having done a great deal of rewriting of make some two years ago I can
tell you that even a small change to make is a tough job testing-wise:
run all the combinations of !-j and -j <N> on all architectures and run
the change through the port-building cluster. That's a warning to start
with.

Second I would start with careful profiling to find out where the
problem actually is. You might be surprised. As an example: several
times the idea came up to use a hash structure instead of linear lists
for make variables. I got a patch for this and - it makes absolutely no
difference performance-wise (well, there was some indication that
performance gets worse, but that was around or below noise level). With
careful I mean to find out who takes the time:

Yes, I must admit that I thought that a hash structure for the variables would greatly increase the speed of make. I rewrote it using Berkeley databases, and like you said - absolutely no difference!! I even tried btrees.



My guess at that time was that because there are actually many variable tables (one per target and the global one) and only a small number of variables in most of the tables the initialisation overhead outweights what you win through the hashing.

As for the profiling - I did some profiling on buildworld then. From the several hours a buildworld took only one or two minutes were used by all the makes. At this point I stopped optimizing make :-) (I don't remember the exact numbers - that was two or three years ago).

harti
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