System call comparison

[Mike Stump]

On Sunday, August 3, 2003, at 02:25 PM, Neil Booth wrote:
> Here are the results for compiling current toplev.c:
> 		Before		After
> Total ex PCH	1416		973		(-31%)
> Total ex PCH	1347		888		(-34%)

Looks nice, thanks.  Next thing to think about would be 100 search 
dirs, 10 files apiece, 10,000 #includes.  While these numbers aren't 
very realistic, if you measure the speed improvements on more normal 
things, I suspect they will win.  In code around here, we see a 30-50% 
compile time speed increase with this change.  :-(

Essentially the change is to readdir once for each -I directory and 
populate a cache that can rule out trying certain include paths.

We should dust it off and submit it...  If you want to work on it, play 
with our patch, just ask and we can send you the code we have...  I'm 
working on the framework code now, which is more important, as it 
provides the semantics, which trump speed (for now).