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From: Scott Carter <scarter AT emware DOT com>
To: "'Gabriel Zachmann'" <zach AT igd DOT fhg DOT de>, cygwin AT sources DOT redhat DOT com
Subject: RE: gmake is slow under cygwin
Date: Tue, 26 Sep 2000 13:57:40 -0600
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I haven't had this problem in my makefiles, but yesterday I happened to be
trying out a makefile that someone else sent me, and I experienced a *huge*
delay. I haven't tried to analyze it, but I did observe this. When the VPATH
is set to any of the following (which, by the way, don't work correctly in
the test makefile) 

VPATH = c:/temp/test/source
VPATH = /cygdrive/c/temp/test/source
VPATH = //c/temp/test/source

There is no long delay. When VPATH is set to this (which is incorrect)

VPATH = //cygdrive/c/temp/test/source

and I do 

make -d

make spits out
-----------------------------------
GNU Make version 3.79, by Richard Stallman and Roland McGrath.
Built for i686-pc-cygwin
Copyright (C) 1988, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99
        Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.

Report bugs to <bug-make AT gnu DOT org>.

Reading makefiles...
Reading makefile `makefile'...
-----------------------------------

and then stalls for about 7 seconds before continuing. I have no idea if you
have a bad VPATH in your makefiles, but this example illustrates that some
errors can cause large delays, and yet otherwise not be reported as errors.

I don't know if any of the following suggestions will appreciably speed up
processing, but I know they relieve make of having to examine a lot of
dead-end possibilities. [NOTE that these may not be desirable/usable in all
circumstances.]

1) Use .PHONY: for all targets that don't correspond to real files.
2) Use .SUFFIXES:#blank to delete all known default suffixes.
3) Add an empty rule (no dependencies, no commands) for "makefile" and any
files it includes.

Good luck
Scott Carter
Software Engineer

-----Original Message-----
From: Gabriel Zachmann [mailto:zach AT igd DOT fhg DOT de]
Sent: Monday, September 25, 2000 03:49 AM
To: cygwin AT sources DOT redhat DOT com
Subject: Re: gmake is slow under cygwin


] --- Gabriel Zachmann <zach AT igd DOT fhg DOT de> wrote:
] > 
] > Any ideas or insights will be highly appreciated,
] > Gab.
] > 
] 
] Any virus scanners running?  See the FAQ.
] 

(Hm, the FAQ didn't say that a virus scanner could incur a performance
penalty, it just said that it might prevent cygwin from functioning ;-)

Ok, I switched McAffee off.
But that reduced execution time only by about 1 sec:
-  with mcaffee running: real time = 7.4 sec, user time = 3.1 sec;
-  mcaffee not running: real = 6 sec, user time = 2.8 sec

That still seems pretty slow for just a few 100 lines of makefiles,
doesn't it?

Cheers,
Gab.


-- 
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| Paradigm is a word too often used by those                          |
| who would like to have a new idea                                   |
| but cannot think of one.                                            |
|                     (Mervyn King, Deputy Governor, Bank of England) |
|                                                                     |
| zach AT igd DOT fhg DOT de          gab AT gab DOT cx        Gabriel DOT Zachmann AT gmx DOT net |
| www.igd.fhg.de/~zach/    www.gab.cx        __@/'                    |
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