raspberrypi
configs: Enable TRANSPARENT_HUGEPAGE_MADVISE
Upstream v3d patches are adding support for big (64K) and super (1MB) pages, which require these options.
See: https://lore.kernel.org/dri-devel/[email protected]/
There are also some potential performance benefits linked from: https://github.com/raspberrypi/linux/pull/6297
Putting this up as a draft PR, so it's not forgotten. We won't get the v3d benefits until we backport them to 6.6, or switch to a newer upstream kernel.
My brief testing suggests TRANSPARENT_HUGEPAGE_MADVISE doesn't have performance hit on NUMA that TRANSPARENT_HUGEPAGE_ALWAYS did, but perhaps wait until NUMA is more final (and we don't spot any other adverse results) before merging this.
Current testing kernels from the rpi-firmware repo now show this in the dmesg:
[ 16.662538] bcm2835_isp: module is from the staging directory, the quality is unknown, you have been warned.
[ 16.678470] v3d fec00000.v3d: [drm] Transparent Hugepage support is recommended for optimal performance on this platform!
[ 16.688136] [drm] Initialized v3d 1.0.0 for fec00000.v3d on minor 0
Yes. A todo is to profile various use cases, including v3d and check what the benefits are, and if any negatives are observed.
Based on the testing TRANSPARENT_HUGEPAGE_MADVISE may well be enabled in future.
We're happy to heard of any positive (or negative) effects from users.