Optimizing away "ReadFile" calls when Make calls stat()

Tue Feb 13 11:01:00 GMT 2001

> Date: 2001年2月13日 13:51:50 -0500
> From: "Larry Hall (RFK Partners, Inc)" <lhall@rfk.com>
>> I know this would only address half the problem but I wonder if it would make
> sense to cache the results of ReadFile() so that separate checks for symbolic
> links and executables would result in only 1 ReadFile() call. This seems
> like a nice general optimization which wouldn't be so "gross"...

I see three problems with that:
1) The cache would have to be automatically invalidated whenever the
 file is changed, and you'd thus need to check if a file has changed
 before using the cache, and those checks would themselves take
 time.
2) Many of our dependencies are checked over and over again in many
 Makefiles by many different Make processes. Thus, either the cache
 you propose would have to be global in the Cygwin shared memory
 segment, or the checks would still happen over and over for us.
3) The implementation of such a global cache would be much more
 complex then the simple changes I implemented in only a couple of
 hours, and I would argue that this complexity would in fact make
 such a cache *more* "gross" than the changes I'm suggesting.
jik
--
Want to unsubscribe from this list?
Check out: http://cygwin.com/ml/#unsubscribe-simple