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freebsd-nq/share/mk/bsd.cpu.mk
Eric van Gyzen ddab052725 Disable SSE in libthr 
Clang emits SSE instructions on amd64 in the common path of
pthread_mutex_unlock.  If the thread does not otherwise use SSE,
this usage incurs a context-switch of the FPU/SSE state, which
reduces the performance of multiple real-world applications by a
non-trivial amount (3-5% in one application).

Instead of this change, I experimented with eagerly switching the
FPU state at context-switch time.  This did not help.  Most of the
cost seems to be in the read/write of memory--as kib@ stated--and
not in the #NM handling.  I tested on machines with and without
XSAVEOPT.

One counter-argument to this change is that most applications already
use SIMD, and the number of applications and amount of SIMD usage
are only increasing.  This is absolutely true.  I agree that--in
general and in principle--this change is in the wrong direction.
However, there are applications that do not use enough SSE to offset
the extra context-switch cost.  SSE does not provide a clear benefit
in the current libthr code with the current compiler, but it does
provide a clear loss in some cases.  Therefore, disabling SSE in
libthr is a non-loss for most, and a gain for some.

I refrained from disabling SSE in libc--as was suggested--because
I can't make the above argument for libc.  It provides a wide variety
of code; each case should be analyzed separately.

https://lists.freebsd.org/pipermail/freebsd-current/2015-March/055193.html

Suggestions from:	dim, jmg, rpaulo
Approved by:	kib (mentor)
MFC after:	2 weeks
Sponsored by:	Dell Inc.
2015-08-05 12:53:55 +00:00

310 lines
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Makefile
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# $FreeBSD$
# Set default CPU compile flags and baseline CPUTYPE for each arch. The
# compile flags must support the minimum CPU type for each architecture but
# may tune support for more advanced processors.
.if !defined(CPUTYPE) || empty(CPUTYPE)
_CPUCFLAGS =
. if ${MACHINE_CPUARCH} == "aarch64"
MACHINE_CPU = arm64
. elif ${MACHINE_CPUARCH} == "amd64"
MACHINE_CPU = amd64 sse2 sse mmx
. elif ${MACHINE_CPUARCH} == "arm"
MACHINE_CPU = arm
. elif ${MACHINE_CPUARCH} == "i386"
MACHINE_CPU = i486
. elif ${MACHINE_CPUARCH} == "mips"
MACHINE_CPU = mips
. elif ${MACHINE_CPUARCH} == "powerpc"
MACHINE_CPU = aim
. elif ${MACHINE_CPUARCH} == "sparc64"
MACHINE_CPU = ultrasparc
. endif
.else
# Handle aliases (not documented in make.conf to avoid user confusion
# between e.g. i586 and pentium)
. if ${MACHINE_CPUARCH} == "amd64" || ${MACHINE_CPUARCH} == "i386"
. if ${CPUTYPE} == "barcelona"
CPUTYPE = amdfam10
. elif ${CPUTYPE} == "core-avx2"
CPUTYPE = haswell
. elif ${CPUTYPE} == "core-avx-i"
CPUTYPE = ivybridge
. elif ${CPUTYPE} == "corei7-avx"
CPUTYPE = sandybridge
. elif ${CPUTYPE} == "corei7"
CPUTYPE = nehalem
. elif ${CPUTYPE} == "slm"
CPUTYPE = silvermont
. elif ${CPUTYPE} == "atom"
CPUTYPE = bonnell
. elif ${CPUTYPE} == "core"
CPUTYPE = prescott
. endif
. if ${MACHINE_CPUARCH} == "amd64"
. if ${CPUTYPE} == "prescott"
CPUTYPE = nocona
. endif
. else
. if ${CPUTYPE} == "k7"
CPUTYPE = athlon
. elif ${CPUTYPE} == "p4"
CPUTYPE = pentium4
. elif ${CPUTYPE} == "p4m"
CPUTYPE = pentium4m
. elif ${CPUTYPE} == "p3"
CPUTYPE = pentium3
. elif ${CPUTYPE} == "p3m"
CPUTYPE = pentium3m
. elif ${CPUTYPE} == "p-m"
CPUTYPE = pentium-m
. elif ${CPUTYPE} == "p2"
CPUTYPE = pentium2
. elif ${CPUTYPE} == "i686"
CPUTYPE = pentiumpro
. elif ${CPUTYPE} == "i586/mmx"
CPUTYPE = pentium-mmx
. elif ${CPUTYPE} == "i586"
CPUTYPE = pentium
. endif
. endif
. elif ${MACHINE_ARCH} == "sparc64"
. if ${CPUTYPE} == "us"
CPUTYPE = ultrasparc
. elif ${CPUTYPE} == "us3"
CPUTYPE = ultrasparc3
. endif
. endif
###############################################################################
# Logic to set up correct gcc optimization flag. This must be included
# after /etc/make.conf so it can react to the local value of CPUTYPE
# defined therein. Consult:
# http://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html
# http://gcc.gnu.org/onlinedocs/gcc/IA_002d64-Options.html
# http://gcc.gnu.org/onlinedocs/gcc/RS_002f6000-and-PowerPC-Options.html
# http://gcc.gnu.org/onlinedocs/gcc/MIPS-Options.html
# http://gcc.gnu.org/onlinedocs/gcc/SPARC-Options.html
# http://gcc.gnu.org/onlinedocs/gcc/i386-and-x86_002d64-Options.html
. if ${MACHINE_CPUARCH} == "i386"
. if ${CPUTYPE} == "crusoe"
_CPUCFLAGS = -march=i686 -falign-functions=0 -falign-jumps=0 -falign-loops=0
. elif ${CPUTYPE} == "k5"
_CPUCFLAGS = -march=pentium
. elif ${CPUTYPE} == "c7"
_CPUCFLAGS = -march=c3-2
. else
_CPUCFLAGS = -march=${CPUTYPE}
. endif
. elif ${MACHINE_CPUARCH} == "amd64"
_CPUCFLAGS = -march=${CPUTYPE}
. elif ${MACHINE_CPUARCH} == "arm"
. if ${CPUTYPE} == "xscale"
#XXX: gcc doesn't seem to like -mcpu=xscale, and dies while rebuilding itself
#_CPUCFLAGS = -mcpu=xscale
_CPUCFLAGS = -march=armv5te -D__XSCALE__
. elif ${CPUTYPE} == "armv6"
_CPUCFLAGS = -march=${CPUTYPE} -DARM_ARCH_6=1
. elif ${CPUTYPE} == "cortexa"
_CPUCFLAGS = -march=armv7 -DARM_ARCH_6=1 -mfpu=vfp
. else
_CPUCFLAGS = -mcpu=${CPUTYPE}
. endif
. elif ${MACHINE_ARCH} == "powerpc"
. if ${CPUTYPE} == "e500"
_CPUCFLAGS = -Wa,-me500 -msoft-float
. else
_CPUCFLAGS = -mcpu=${CPUTYPE} -mno-powerpc64
. endif
. elif ${MACHINE_ARCH} == "powerpc64"
_CPUCFLAGS = -mcpu=${CPUTYPE}
. elif ${MACHINE_CPUARCH} == "mips"
. if ${CPUTYPE} == "mips32"
_CPUCFLAGS = -march=mips32
. elif ${CPUTYPE} == "mips32r2"
_CPUCFLAGS = -march=mips32r2
. elif ${CPUTYPE} == "mips64"
_CPUCFLAGS = -march=mips64
. elif ${CPUTYPE} == "mips64r2"
_CPUCFLAGS = -march=mips64r2
. elif ${CPUTYPE} == "mips4kc"
_CPUCFLAGS = -march=4kc
. elif ${CPUTYPE} == "mips24kc"
_CPUCFLAGS = -march=24kc
. endif
. elif ${MACHINE_ARCH} == "sparc64"
. if ${CPUTYPE} == "v9"
_CPUCFLAGS = -mcpu=v9
. elif ${CPUTYPE} == "ultrasparc"
_CPUCFLAGS = -mcpu=ultrasparc
. elif ${CPUTYPE} == "ultrasparc3"
_CPUCFLAGS = -mcpu=ultrasparc3
. endif
. endif
# Set up the list of CPU features based on the CPU type. This is an
# unordered list to make it easy for client makefiles to test for the
# presence of a CPU feature.
. if ${MACHINE_CPUARCH} == "i386"
. if ${CPUTYPE} == "bdver4"
MACHINE_CPU = xop avx2 avx sse42 sse41 ssse3 sse4a sse3 sse2 sse mmx k6 k5 i586
. elif ${CPUTYPE} == "bdver3" || ${CPUTYPE} == "bdver2" || \
${CPUTYPE} == "bdver1"
MACHINE_CPU = xop avx sse42 sse41 ssse3 sse4a sse3 sse2 sse mmx k6 k5 i586
. elif ${CPUTYPE} == "btver2"
MACHINE_CPU = avx sse42 sse41 ssse3 sse4a sse3 sse2 sse mmx k6 k5 i586
. elif ${CPUTYPE} == "btver1"
MACHINE_CPU = ssse3 sse4a sse3 sse2 sse mmx k6 k5 i586
. elif ${CPUTYPE} == "amdfam10"
MACHINE_CPU = athlon-xp athlon k7 3dnow sse4a sse3 sse2 sse mmx k6 k5 i586
. elif ${CPUTYPE} == "opteron-sse3" || ${CPUTYPE} == "athlon64-sse3"
MACHINE_CPU = athlon-xp athlon k7 3dnow sse3 sse2 sse mmx k6 k5 i586
. elif ${CPUTYPE} == "opteron" || ${CPUTYPE} == "athlon64" || \
${CPUTYPE} == "athlon-fx"
MACHINE_CPU = athlon-xp athlon k7 3dnow sse2 sse mmx k6 k5 i586
. elif ${CPUTYPE} == "athlon-mp" || ${CPUTYPE} == "athlon-xp" || \
${CPUTYPE} == "athlon-4"
MACHINE_CPU = athlon-xp athlon k7 3dnow sse mmx k6 k5 i586
. elif ${CPUTYPE} == "athlon" || ${CPUTYPE} == "athlon-tbird"
MACHINE_CPU = athlon k7 3dnow mmx k6 k5 i586
. elif ${CPUTYPE} == "k6-3" || ${CPUTYPE} == "k6-2" || ${CPUTYPE} == "geode"
MACHINE_CPU = 3dnow mmx k6 k5 i586
. elif ${CPUTYPE} == "k6"
MACHINE_CPU = mmx k6 k5 i586
. elif ${CPUTYPE} == "k5"
MACHINE_CPU = k5 i586
. elif ${CPUTYPE} == "skylake" || ${CPUTYPE} == "knl"
MACHINE_CPU = avx512 avx2 avx sse42 sse41 ssse3 sse3 sse2 sse i686 mmx i586
. elif ${CPUTYPE} == "broadwell" || ${CPUTYPE} == "haswell"
MACHINE_CPU = avx2 avx sse42 sse41 ssse3 sse3 sse2 sse i686 mmx i586
. elif ${CPUTYPE} == "ivybridge" || ${CPUTYPE} == "sandybridge"
MACHINE_CPU = avx sse42 sse41 ssse3 sse3 sse2 sse i686 mmx i586
. elif ${CPUTYPE} == "westmere" || ${CPUTYPE} == "nehalem" || \
${CPUTYPE} == "silvermont"
MACHINE_CPU = sse42 sse41 ssse3 sse3 sse2 sse i686 mmx i586
. elif ${CPUTYPE} == "penryn"
MACHINE_CPU = sse41 ssse3 sse3 sse2 sse i686 mmx i586
. elif ${CPUTYPE} == "core2" || ${CPUTYPE} == "bonnell"
MACHINE_CPU = ssse3 sse3 sse2 sse i686 mmx i586
. elif ${CPUTYPE} == "yonah" || ${CPUTYPE} == "prescott"
MACHINE_CPU = sse3 sse2 sse i686 mmx i586
. elif ${CPUTYPE} == "pentium4" || ${CPUTYPE} == "pentium4m" || \
${CPUTYPE} == "pentium-m"
MACHINE_CPU = sse2 sse i686 mmx i586
. elif ${CPUTYPE} == "pentium3" || ${CPUTYPE} == "pentium3m"
MACHINE_CPU = sse i686 mmx i586
. elif ${CPUTYPE} == "pentium2"
MACHINE_CPU = i686 mmx i586
. elif ${CPUTYPE} == "pentiumpro"
MACHINE_CPU = i686 i586
. elif ${CPUTYPE} == "pentium-mmx"
MACHINE_CPU = mmx i586
. elif ${CPUTYPE} == "pentium"
MACHINE_CPU = i586
. elif ${CPUTYPE} == "c7"
MACHINE_CPU = sse3 sse2 sse i686 mmx i586
. elif ${CPUTYPE} == "c3-2"
MACHINE_CPU = sse i686 mmx i586
. elif ${CPUTYPE} == "c3"
MACHINE_CPU = 3dnow mmx i586
. elif ${CPUTYPE} == "winchip2"
MACHINE_CPU = 3dnow mmx
. elif ${CPUTYPE} == "winchip-c6"
MACHINE_CPU = mmx
. endif
MACHINE_CPU += i486
. elif ${MACHINE_CPUARCH} == "amd64"
. if ${CPUTYPE} == "bdver4"
MACHINE_CPU = xop avx2 avx sse42 sse41 ssse3 sse4a sse3
. elif ${CPUTYPE} == "bdver3" || ${CPUTYPE} == "bdver2" || \
${CPUTYPE} == "bdver1"
MACHINE_CPU = xop avx sse42 sse41 ssse3 sse4a sse3
. elif ${CPUTYPE} == "btver2"
MACHINE_CPU = avx sse42 sse41 ssse3 sse4a sse3
. elif ${CPUTYPE} == "btver1"
MACHINE_CPU = ssse3 sse4a sse3
. elif ${CPUTYPE} == "amdfam10"
MACHINE_CPU = k8 3dnow sse4a sse3
. elif ${CPUTYPE} == "opteron-sse3" || ${CPUTYPE} == "athlon64-sse3" || \
${CPUTYPE} == "k8-sse3"
MACHINE_CPU = k8 3dnow sse3
. elif ${CPUTYPE} == "opteron" || ${CPUTYPE} == "athlon64" || \
${CPUTYPE} == "athlon-fx" || ${CPUTYPE} == "k8"
MACHINE_CPU = k8 3dnow
. elif ${CPUTYPE} == "skylake" || ${CPUTYPE} == "knl"
MACHINE_CPU = avx512 avx2 avx sse42 sse41 ssse3 sse3
. elif ${CPUTYPE} == "broadwell" || ${CPUTYPE} == "haswell"
MACHINE_CPU = avx2 avx sse42 sse41 ssse3 sse3
. elif ${CPUTYPE} == "ivybridge" || ${CPUTYPE} == "sandybridge"
MACHINE_CPU = avx sse42 sse41 ssse3 sse3
. elif ${CPUTYPE} == "westmere" || ${CPUTYPE} == "nehalem" || \
${CPUTYPE} == "silvermont"
MACHINE_CPU = sse42 sse41 ssse3 sse3
. elif ${CPUTYPE} == "penryn"
MACHINE_CPU = sse41 ssse3 sse3
. elif ${CPUTYPE} == "core2" || ${CPUTYPE} == "bonnell"
MACHINE_CPU = ssse3 sse3
. elif ${CPUTYPE} == "nocona"
MACHINE_CPU = sse3
. endif
MACHINE_CPU += amd64 sse2 sse mmx
. elif ${MACHINE_ARCH} == "powerpc"
. if ${CPUTYPE} == "e500"
MACHINE_CPU = booke
. endif
. elif ${MACHINE_ARCH} == "sparc64"
. if ${CPUTYPE} == "v9"
MACHINE_CPU = v9
. elif ${CPUTYPE} == "ultrasparc"
MACHINE_CPU = v9 ultrasparc
. elif ${CPUTYPE} == "ultrasparc3"
MACHINE_CPU = v9 ultrasparc ultrasparc3
. endif
. endif
.endif
.if ${MACHINE_CPUARCH} == "mips"
CFLAGS += -G0
.endif
.if ${MACHINE_ARCH} == "armv6"
_CPUCFLAGS += -mfloat-abi=softfp
.endif
# NB: COPTFLAGS is handled in /usr/src/sys/conf/kern.pre.mk
.if !defined(NO_CPU_CFLAGS)
CFLAGS += ${_CPUCFLAGS}
.endif
#
# Prohibit the compiler from emitting SIMD instructions.
# These flags are added to CFLAGS in areas where the extra context-switch
# cost outweighs the advantages of SIMD instructions.
#
# gcc:
# Setting -mno-mmx implies -mno-3dnow
# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
#
# clang:
# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and
# -mno-sse42
# (-mfpmath= is not supported)
#
.if ${MACHINE_CPUARCH} == "i386" || ${MACHINE_CPUARCH} == "amd64"
CFLAGS_NO_SIMD.clang= -mno-avx
CFLAGS_NO_SIMD= -mno-mmx -mno-sse
.endif
CFLAGS_NO_SIMD += ${CFLAGS_NO_SIMD.${COMPILER_TYPE}}
# Add in any architecture-specific CFLAGS.
# These come from make.conf or the command line or the environment.
CFLAGS += ${CFLAGS.${MACHINE_ARCH}}
CXXFLAGS += ${CXXFLAGS.${MACHINE_ARCH}}
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