https://bugs.freedesktop.org/show_bug.cgi?id=31635
Summary: Bad performance of 64-bit compilation compared to 32-bit. Product: Mesa Version: git Platform: x86-64 (AMD64) OS/Version: Linux (All) Status: NEW Severity: normal Priority: medium Component: Drivers/Gallium/r300 AssignedTo: dri-devel@lists.freedesktop.org ReportedBy: drill87@gmail.com
I've got archlinux 64-bit system with chrooted archlinux 32-bit in it. Video card: ATI X1270 (RS690) Kernel version: 2.6.35 Xorg server version: 1.9.0
I've compiled r300g both for 32-bit and 64-bit systems with parameters: --prefix=/usr --enable-glx-tls --disable-egl --enable-gallium-radeon --with-dri-driverdir=/usr/lib/xorg/modules/dri --with-dri-drivers="radeon,r300" --with-state-trackers="glx,dri"
After tests I found, that in 32-bit r300g gives 860 fps in glxgears, whereas 64-bit version only 250. I also compared framerate in 3D action game Tremulous, which has precompiled binaries for both 32-bit and 64-bit linux - the result was similar: I've got 38 fps in 32-bit version and only 18 fps in 64-bit in same scene.
Unfortunately, I'm not sure if this is a real bug or just a bad optimization of 64-bit version - I couldn't find any specific information about that...