Re: Two strange messages while building Emacs on MS-Windows

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Date: Sun, 09 Dec 2012 10:50:31 -0500
> Cc: emacs-devel@gnu.org, dmoncayo@gmail.com
> 
> I do "make -j2" and get about %170 of cpu utilisation (most of the
> less-than-100% is due to phases in the build process where we only have
> one process running, such as when running `configure'), so presumably my
> 6min would turn into no more than 10min if run sequentially.

FWIW, "make -j2 bootstrap" was timed as follows:

  real    17m2.832s
  user    23m4.760s
  sys     4m45.010s

on this machine:

  Linux fencepost.gnu.org 2.6.32-42-server #1trisquel3 SMP Sat Aug 11 18:02:12 UTC 2012 x86_64 GNU/Linux

whose /proc/cpuinfo says, inter alia:

  vendor_id       : AuthenticAMD
  cpu family      : 16
  model           : 9
  model name      : AMD Opteron(tm) Processor 6128
  stepping        : 1
  cpu MHz         : 2000.078
  cache size      : 512 KB

This machine was 98% idle when I timed the bootstrap.

This command:

   time emacs --batch --eval '(message "Hello")'

(with an unoptimized build of Emacs) takes between 0.085s and 0.123s
on this machine.  (Why this is 5 times slower than Óscar's slower
machine is also unclear.)

The command "cd lisp && make compile-always", which sequentially
compiles every Lisp file, was timed on this machine as follows:

  real    23m11.277s
  user    16m50.820s
  sys     2m45.910s

The same command with "make -j2" times like this:

  real    11m51.381s
  user    17m15.850s
  sys     2m49.410s

which is an entirely reasonable 2-fold speedup in the elapsed time
(and seems to reveal some bug in accounting for user- and
system-times).

According to http://www.cpubenchmark.net, the CPU marks of the
machines mentioned in this thread are, top to bottom:

  Intel Core i7-2600      8,628
  AMD Opteron 6128        4,999
  Intel Core i5-2410M     3,186
  Intel Core2 Quad Q6600  2,941
  Intel Core 2 duo T9300  1,709

So I have no idea how Stefan gets a 6-min bootstrap on his 2.5-GHz
T9300 Core 2 duo...  Probably missing some factor here.  I thought
maybe the filesystem used on fencepost could be it, but "df -hT ."
there says:

  Filesystem    Type    Size  Used Avail Use% Mounted on
  /dev/xvdb1    ext4    493G  378G  115G  77% /srv/data

and my, perhaps incorrect, reading of that is that this is a local
ext4 filesystem.