I had uncachable entries in /proc/mtrr. My Asus P5K Deluxe does not have a MTRR option and while it had a memory remapping option, that option was already on. I was able to change these entries to writeback by enabling MTRR cleanup. This can be done either through the use of kernel parameters or by recompiling the kernel. The Nvidia guide should include information on how to do this for systems where changing BIOS settings is not an option. Here are my references: http://linuxindetails.wordpress.com/category/x11/ http://en.gentoo-wiki.com/wiki/MTRR Reproducible: Always Steps to Reproduce:
If you can provide a simple explanation and which lines of the guide it should be added to, so that I don't have to go digging through blogs and wikis, then sure. It can even be plain text; it doesn't have to be GuideXML. Otherwise, I'm afraid I don't have anything clear enough to go on for your workaround. I've never had MTRR issues for any of my nVidia or ATI cards.
I apologize for not responding sooner. I had to attend a funeral for a friend who died recently. Anyway, a known issue exists on Intel 64-bit systems with 4GB of RAM or more where the CPU's MTRR registers are configured by the BIOS to disable the cache hierarchy for certain regions of memory, specifically those regions used to map external memory present on addin boards like graphics cards. This can result in noticeable lag on systems using graphical desktop environments. This is not a graphics issue per se, but people might suspect their system's graphics card and/or graphics drivers are at fault for it. Resolving this requires compiling the Linux kernel with the follow options set: Processor type and features ---> [*] MTRR (Memory Type Range Register) support [*] MTRR cleanup support (1) MTRR cleanup enable value (0-1) (1) MTRR cleanup spare reg num (0-7) Alternatively, you can append "enable_mtrr_cleanup mtrr_spare_reg_nr=1" appended to your kernel parameters provided that your kernel was provided with CONFIG_MTRR_SANITIZER=y. For those unaware, CONFIG_MTRR_SANITIZER is the MTRR cleanup support option above. This might be more desirable than specifying these options in your kernel.
