On Mon, Nov 12, 2018 at 03:26:49PM -0800, Daniel Verkamp wrote: > 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). As long as the default behavior isn't changed, I think rough good performance is ok. Applied, thanks! > Daniel Verkamp (2): > lib/raid6: sort algos in rough performance order > lib/raid6: add option to skip algo benchmarking > > include/linux/raid/pq.h | 3 ++ > lib/Kconfig | 8 ++++ > lib/raid6/algos.c | 81 ++++++++++++++++++++++------------------- > 3 files changed, 54 insertions(+), 38 deletions(-) > > -- > 2.19.1.930.g4563a0d9d0-goog >
