Gentoo Archives: gentoo-dev

From: Daniel Robbins <drobbins@g.o>
To: gentoo-dev@g.o
Subject: [gentoo-dev] [ Why make(1) sucks]
Date: Mon, 18 Jun 2001 16:16:28
1 Hi All,
3 Thought some people may be interested in this email from the dietlibc
4 mailing list. This is one of the reasons we don't use "make" for our
5 ports system.
7 ----- Forwarded message from Felix von Leitner <leitner@××××.de> -----
9 To: dietlibc@××××.de
10 Date: Mon, 18 Jun 2001 22:45:47 +0200
11 From: Felix von Leitner <leitner@××××.de>
12 Subject: Why make(1) sucks
14 If you compile the diet libc frequently, you probably noticed that
15 running make takes over one second before even running any command.
16 If you look at the Makefile, you will notice that it contains a lot of
17 dynamic features like wildcard and patsubst and a long list of VPATHs.
18 So I assumed that these were the parts that ate all the time and wrote a
19 perl script that a) removes the wildcards and patsubsts by expanding
20 them in-line and b) computing the dependencies statically and stating
21 them explicitly.
23 I checked in that script as contrib/ It will write the new
24 Makefile to sMakefile. I expected a noticeable performance increase in
25 make after the first part was done (remove wildcard and patsubst), but
26 the pause increased to 7.5 seconds on my Athlon 900. Huh?
28 Well, maybe the VPATHs are the part that takes so long, I thought, so I
29 added the b) part. The pause decreased to 7.0 seconds. I couldn't
30 believe it and put the dynamic wildcard and patsubst part back in, and
31 now make again takes 1 second. Adding a syntax error in the end
32 revealed that make apparently takes one full second to parse the
33 Makefile!
35 Switching to a perl script would increase performance tenfold!
36 This can't be true, can it?
38 So I did an strace and found out that every occurrance of $(OBJDIR)
39 prompted make to recalculate $(ARCH), i.e. run uname and sed!
41 Now that I see why make sucks, I'm working on a solution. The obvious
42 solution is to simply run make again setting MYARCH to something. When
43 I do that with the static dependencies, make takes 0.08 seconds to
44 notice that it does not have to do anything.
46 Felix
49 ----- End forwarded message -----
51 --
52 Daniel Robbins <drobbins@g.o>
53 President/CEO
54 Gentoo Technologies, Inc.


Subject Author
Re: [gentoo-dev] [ Why make(1) sucks] John Allen <john.allen@××××××.ie>