Re: [Automake-NG] [PATCH 1/2] [ng] perf: disable GNU make builtin rules, for performance reasons

[Dave Hart]

On Wed, Jun 27, 2012 at 17:30 PM, Bob Friesenhahn wrote:
> On Wed, 27 Jun 2012, Stefano Lattarini wrote:
>
>> * lib/am/header-vars (MAKEFLAGS): Append '--no-builtin-rules'.  This
>> enhance performance by removing GNU make builtin rules that would be
>> rather irrelevant (e.g., rules to automatically check out files from
>> from RCS or SCCS repositories), or overridden by Automake (e.g., rules
>> to compile C or C++ files).  With this simple tweak, the null-build
>> time on GNU coreutils on an aging Debian system goes down from ~ 20
>> seconds to ~ 9 seconds.
>
>
> This simple approach seems like a huge improvement.  The improvement will
> surely be larger if some/all of the files are accessed over a network.

Yes, good stuff.  Anyone who has debugged Makefiles with GNU make -v
has seen the insane number of wasted operations due to combinatorial
explosion exploring possible matches with builtin rules.

Can Automake be similarly improved to disable GNU make's builtin rules
without sacraficing compatibility with less-loved make
implementations?  If it's not practical for Automake to do this for
all packages, how might a maintainer do it for his package without
requiring GNU make?

Cheers,
Dave Hart