On a kernel with BTRFS built in, RAID6_PQ is always selected, which means the init-time benchmarking is always performed. This takes a significant amount of time during boot, and it isn't particularly useful if the RAID modes of BTRFS are not actually used. This patch series adds a config option to skip the benchmarking and just choose the first valid algorithm. This seems like the least bad option; suggestions for other less-hacky approaches are welcome! The general approach was inspired by a patch from Clear Linux: https://github.com/clearlinux-pkgs/linux-lts/blob/master/0115-raid6-add-Kconfig-option-to-skip-raid6-benchmarking.patch However, instead of hard-coding a specific implementation of each algorithm via config option, this patch set just sorts the lists of algorithms so that they are in rough order of performance and then chooses the first one. This isn't perfect, as the performance of each algorithm may vary depending on processor microarchitecture or other implementation details, but it's good enough for our purposes (and the default configuration still benchmarks all algorithms, so there is no change in behavior unless the config is explicitly disabled). Daniel Verkamp (2): lib/raid6: sort algos in rough performance order lib/raid6: add option to skip algo benchmarking include/linux/raid/pq.h | 8 +++- lib/Kconfig | 8 ++++ lib/raid6/algos.c | 81 ++++++++++++++++++++++------------------- lib/raid6/test/Makefile | 3 ++ 4 files changed, 61 insertions(+), 39 deletions(-) -- 2.19.1.930.g4563a0d9d0-goog
