[Mesa-dev] glxgears performance higher with software renderer compared to h/w drivers

[Divick Kishore]

Hi,
     I am trying to build s/w only mesa driver. It seems that the
performance of software only renderer (compiled with
--with-driver=xlib) is higher than that of h/w drivers. Could someone
please help me understand what is causing this or if it is expected?

I see that dri based s/w renderer is also slower than xlib/swrast
driver. So how does dri based s/w rendering work and why is it slower
than xlib/swrast driver?

I presume that --with-driver=xlib builds s/w only renderer. Please
correct me if I am wrong.

./configure -build=x86_64-linux-gnu --with-driver=dri
--with-dri-drivers="i915 swrast"
--with-dri-driverdir=/home/divick/work/mesa/mesa-8.0.5/build/dri/x86_64-linux-gnu/
--with-dri-searchpath='/home/divick/work/mesa/mesa-8.0.5/build/dri/x86_64-linux-gnu/'
--enable-glx-tls --enable-shared-glapi --enable-texture-float
--enable-xa --enable-driglx-direct --with-egl-platforms="x11 drm"
--enable-gallium-llvm --with-gallium-drivers="swrast i915"
--enable-gles1 --enable-gles2 --enable-openvg --enable-gallium-egl
--disable-glu CFLAGS="-Wall -g -O2" CXXFLAGS="-Wall -g -O2"

with LIBGL_ALWAYS_SOFTWARE=1
glxgears reports:

GL_RENDERER   = Software Rasterizer
GL_VERSION    = 2.1 Mesa 8.0.5
GL_VENDOR     = Mesa Project

fps: ~ 490 fps

Without LIBGL_ALWAYS_SOFTWARE set:

GL_RENDERER   = Mesa DRI Intel(R) Sandybridge Mobile
GL_VERSION    = 3.0 Mesa 8.0.5
GL_VENDOR     = Tungsten Graphics, Inc

fps: ~ 60

When compiled with configure options

 --build=x86_64-linux-gnu --disable-egl --with-gallium-drivers=
--with-driver=xlib --disable-egl CFLAGS="-Wall -g -O2" CXXFLAGS="-Wall
-g -O2"

glxgears reports:

GL_RENDERER   = Mesa X11
GL_VERSION    = 2.1 Mesa 8.0.5
GL_VENDOR     = Brian Paul

fps: ~1600

With drivers installed on system and with LIBGL_ALWAYS_SOFTWARE=1:

GL_RENDERER   = Gallium 0.4 on llvmpipe (LLVM 0x209)
GL_VERSION    = 2.1 Mesa 8.0.5
GL_VENDOR     = VMware, Inc.

fps: ~ 1130

Thanks & Regards,
Divick