[cmake-developers] dependency scanning speed

[Alexander Neundorf]

On Sunday 10 September 2006 09:19, Alexander Neundorf wrote:
> On Sunday 10 September 2006 01:19, you wrote:
> ...
>
> > did you use valgrind's callgrind tool to profile this? I think you'll
> > really get more concrete data on what's taking up the most time by using
> > that tool. :)
>
> Not yet.
> From my knowledge of this code, this is basically a lot of dealing with STL
> strings and string containters and some stat()ing.
> I would guess that one must try to reduce the work actually done by caching
> even more information.

"some stating" was slightly wrong it seems.
Here are the numbers:
-each source files is stat()ed once, gives 1921 stat()
-the includecache files are stated once for each source file. give 1858 stat()
 -> these could be reduced to 2 stat() calls, would save 1856 stat(), not 
*that* much
-495,388 access() calls with relative paths, might be tricky to cache
-2,851,201 access() calls with absolute paths for 27,666 different paths, 
should be easy to cache. This would remove 2,823,535 access() calls.

/me goes testing

Alex
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