freebsd-nq/share/mk/bsd.opts.mk
Bryan Drewery cf1eeb33be Add a FAST_DEPEND option, off by default, which speeds up the build significantly.
This speeds up buildworld by 16% on my system and buildkernel by 35%.

Rather than calling mkdep(1), which is just a wrapper around 'cc -E',
use the modern -MD -MT -MF flags to gather and generate dependencies during
compilation.  This flag was introduced in GCC "a long time ago", in GCC 3.0,
and is also supported by Clang.  (It appears that ICC also supports this but I
do not have access to test it).  This avoids running the preprocessor *twice*
for every build, in both 'make depend' and 'make all'.  This is especially
noticeable when using ccache since it does not cache preprocessor results from
mkdep(1) / 'cc -E', but still speeds up compilation with the -MD flags.

For 'make depend' a tree-walk is still done to ensure that all DPSRCS
are generated when expected, and that beforedepend/afterdepend and
_EXTRADEPEND are all still respected.  In time this may change but for now
I've been conservative.  The time for a tree-walk with -j combined with
SUBDIR_PARALLEL is not significant.  For example, it takes about 9 seconds
with -j15 to walk all of src/ for 'make depend' now on my system.

A .depend file is still generated with the various rules that apply to
the final target, or custom rules.  Otherwise there are now
per-built-object-file .depend files, such as .depend.filename.o.  These
are included directly by make rather than populating .depend with a loop
and .depend lines, which only added overhead to the now almost-NOP 'make
depend' phase.

Before this I experimented with having mkdep(1) called in parallel per-file.
While this improved the kernel and lib/libc 'make depend' phase, it resulted
in slower build times overall.

The -M flags are removed from CFLAGS when linking since they have no effect.

Enabling this by default, for src or out-of-src, can be done once more testing
has been done, such as a ports exp-run, and with more compilers.

The system I used for testing was:
  WITNESS
  Build options: -j20 WITH_LLDB=yes WITH_DEBUG_FILES=yes WITH_FAST_DEPEND=yes
  DISK: ZFS 3-way mirror with very slow disks using SSD l2arc/log.
        The arc was fully populated with src tree files.
  RAM: 76GiB
  CPU: Intel(R) Xeon(R) CPU L5520 @2.27GHz
       2 package(s) x 4 core(s) x 2 SMT threads = hw.ncpu=16

buildworld:
  x buildworld-before
  + buildworld-fastdep
  +-------------------------------------------------------------------------------+
  |+                                                                              |
  |+                                                                              |
  |+                                                                       xx    x|
  |                                                                       |_MA___||
  |A                                                                              |
  +-------------------------------------------------------------------------------+
      N           Min           Max        Median           Avg        Stddev
  x   3       3744.13       3794.31       3752.25     3763.5633     26.935139
  +   3       3153.34       3155.16        3154.2     3154.2333    0.91045776
  Difference at 95.0% confidence
          -609.33 +/- 43.1943
          -16.1902% +/- 1.1477%
          (Student's t, pooled s = 19.0569)

buildkernel:
  x buildkernel-before
  + buildkernel-fastdep
  +-------------------------------------------------------------------------------+
  |+                                                                            x |
  |++                                                                           xx|
  |                                                                             A||
  |A|                                                                             |
  +-------------------------------------------------------------------------------+
      N           Min           Max        Median           Avg        Stddev
  x   3        571.57        573.94        571.79     572.43333     1.3094401
  +   3        369.12        370.57         369.3     369.66333    0.79033748
  Difference at 95.0% confidence
          -202.77 +/- 2.45131
          -35.4225% +/- 0.428227%
          (Student's t, pooled s = 1.0815)

Sponsored by:	EMC / Isilon Storage Division
MFC after:	3 weeks
Relnotes:	yes
2015-11-06 04:45:29 +00:00

109 lines
2.9 KiB
Makefile

# $FreeBSD$
#
# Option file for src builds.
#
# Users define WITH_FOO and WITHOUT_FOO on the command line or in /etc/src.conf
# and /etc/make.conf files. These translate in the build system to MK_FOO={yes,no}
# with sensible (usually) defaults.
#
# Makefiles must include bsd.opts.mk after defining specific MK_FOO options that
# are applicable for that Makefile (typically there are none, but sometimes there
# are exceptions). Recursive makes usually add MK_FOO=no for options that they wish
# to omit from that make.
#
# Makefiles must include bsd.mkopt.mk before they test the value of any MK_FOO
# variable.
#
# Makefiles may also assume that this file is included by bsd.own.mk should it
# need variables defined there prior to the end of the Makefile where
# bsd.{subdir,lib.bin}.mk is traditionally included.
#
# The old-style YES_FOO and NO_FOO are being phased out. No new instances of them
# should be added. Old instances should be removed since they were just to
# bridge the gap between FreeBSD 4 and FreeBSD 5.
#
# Makefiles should never test WITH_FOO or WITHOUT_FOO directly (although an
# exception is made for _WITHOUT_SRCONF which turns off this mechanism
# completely).
#
.if !target(__<bsd.opts.mk>__)
__<bsd.opts.mk>__:
.if !defined(_WITHOUT_SRCCONF)
#
# Define MK_* variables (which are either "yes" or "no") for users
# to set via WITH_*/WITHOUT_* in /etc/src.conf and override in the
# make(1) environment.
# These should be tested with `== "no"' or `!= "no"' in makefiles.
# The NO_* variables should only be set by makefiles for variables
# that haven't been converted over.
#
# Only these options are used by bsd.*.mk. KERBEROS and OPENSSH are
# unforutnately needed to support statically linking the entire
# tree. su(1) wouldn't link since it depends on PAM which depends on
# ssh libraries when building with OPENSSH, and likewise for KERBEROS.
# All other variables used to build /usr/src live in src.opts.mk
# and variables from both files are documented in src.conf(5).
__DEFAULT_YES_OPTIONS = \
ASSERT_DEBUG \
DOCCOMPRESS \
INCLUDES \
INSTALLLIB \
KERBEROS \
MAN \
MANCOMPRESS \
NIS \
NLS \
OPENSSH \
PROFILE \
SSP \
SYMVER \
TOOLCHAIN \
WARNS
__DEFAULT_NO_OPTIONS = \
FAST_DEPEND \
CTF \
DEBUG_FILES \
INSTALL_AS_USER \
STALE_STAGED
# meta mode related
__DEFAULT_DEPENDENT_OPTIONS = \
STAGING_MAN/STAGING \
STAGING_PROG/STAGING \
.include <bsd.mkopt.mk>
#
# Supported NO_* options (if defined, MK_* will be forced to "no",
# regardless of user's setting).
#
# These are transitional and will disappaer in the FreeBSD 12.
#
.for var in \
CTF \
DEBUG_FILES \
INSTALLLIB \
MAN \
PROFILE \
WARNS
.if defined(NO_${var})
# This warning may be premature...
#.warning "NO_${var} is defined, but deprecated. Please use MK_${var}=no instead."
MK_${var}:=no
.endif
.endfor
.if ${MK_STAGING} == "no"
MK_STALE_STAGED= no
.endif
.endif # !_WITHOUT_SRCCONF
.endif