my make.conf

# Please consult /usr/share/portage/config/make.conf.example for a more
# detailed example.
#CFLAGS="-O2 -pipe"
#CXXFLAGS="${CFLAGS}"
# WARNING: Changing your CHOST is not something that should be done lightly.
# Please consult http://www.gentoo.org/doc/en/change-chost.xml before changing.
#CHOST="x86_64-pc-linux-gnu"
# These are the USE flags that were used in addition to what is provided by the
# profile used for building.
#USE="mmx sse sse2"
#CC="clang"
#CXX="clang++"
#CXX="clang++ -stdlib=libc++"
CFLAGS="-flto -march=native -O2 -pipe -fomit-frame-pointer -w"
CXXFLAGS="${CFLAGS}"
CHOST="x86_64-pc-linux-gnu"
ACCEPT_KEYWORDS="~amd64"
PKGDIR="/usr/packages"
MAKEOPTS="-j3"
DISTDIR="/usr/distfiles"
PORTAGE_TMPDIR=/tmp
GRUB_PLATFORMS="pc"
ACCEPT_LICENSE="*"
FEATURES="parallel-fetch clean-logs  metadata-transfer  sandbox fail-clean"   #ccache metadata-transfer
#CCACHE_SIZE="15G"
INPUT_DEVICES="evdev keyboard mouse "
VIDEO_CARDS="r600 r700 radeon"
PORTDIR_OVERLAY="/gentoo/linux/ebuild"
LINGUAS="en_US zh_CN "
PYTHON_TARGETS="python2_7    python3_3 "
DRACUT_MODULES="plymouth btrfs systemd"
QEMU_USER_TARGETS="i386  x86_64"
QEMU_SOFTMMU_TARGETS="i386 x86_64"
source /usr/overplay/make.conf
#FETCHCOMMAND="/usr/bin/aria2c -j 8  -t 5   -d  \${DISTDIR}  -o  \${FILE} \${URI}"
#RESUMECOMMAND="${FETCHCOMMAND}"
FETCHCOMMAND="/usr/bin/axel -a -n 8  -o \${DISTDIR}/\${FILE} \${URI}"
RESUMECOMMAND="${FETCHCOMMAND}"
GENTOO_MIRRORS="
http://mirrors.163.com/gentoo
rsync://mirrors.tds.net/gentoo"
SYNC="rsync://rsync26.us.gentoo.org/gentoo-portage"
#SYNC="rsync://mirrors.ustc.edu.cn/gentoo-portage/"
USE_PYTHON="2.7 3.3"
USE="dbus cups alsa -bluetooth consolekit systemd -openrc \
#display
X gles gles2 egl wayland opengl fbcon vaapi vdpau -opencl  \
#cpu
mmx mmx2 sse sse2 ssse3 3dnow 3dnowext mmxext threads  custom-cflags  \
#font
fontconfig xft -cleartype truetype cjk nls unicode lcdfilter \
#destkop
gtk gtk2 gtk3 qt3support kde kde4 qt qt4 icu -gnome -webkit \
#video
vlc gstreamer x264  real direct2d directfb xvmc bluray ffmpeg mpeg  rtmp \
#audio
mp3 midi jack faac timidity lash -pulseaudio \
#image
jpeg mng png imlib jpeg2k gif tiff "