Hi all, For a long time, the maintainers have had a gut feeling that we could optimize performance of XFS filesystems on non-mechanical storage by scaling the number of allocation groups to be a multiple of the CPU count. With modern ~2022 hardware, it is common for systems to have more than four CPU cores and non-striped SSDs ranging in size from 256GB to 4TB. The default mkfs geometry still defaults to 4 AGs regardless of core count, which was settled on in the age of spinning rust. This patchset adds a different computation for AG count and log size that is based entirely on a desired level of concurrency. If we detect storage that is non-rotational (or the sysadmin provides a CLI option), then we will try to match the AG count to the CPU count to minimize AGF contention and make the log large enough to minimize grant head contention. If you're going to start using this code, I strongly recommend pulling from my git trees, which are linked below. This has been running on the djcloud for months with no problems. Enjoy! Comments and questions are, as always, welcome. --D xfsprogs git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=mkfs-scale-geo-on-ssds fstests git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfstests-dev.git/log/?h=mkfs-scale-geo-on-ssds --- tests/xfs/1842 | 51 +++++++++++++++ tests/xfs/1842.out | 177 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 228 insertions(+) create mode 100755 tests/xfs/1842 create mode 100644 tests/xfs/1842.out
