[bionic/linux-gcp][PATCH 0/2] linux-gcp: Reduce boot latency due to RAID6_PQ

Marcelo Henrique Cerri marcelo.cerri at canonical.com
Mon Jan 21 18:55:29 UTC 2019

BugLink: http://bugs.launchpad.net/bugs/1812728

RAID6_PQ tests several algorithms in other to pick the fastest option, but it
performs this test weather the system is using RAID6 or not. Unfortunately
several other modules and file systems have a hard dependency on RAID6_PQ.

In other to workaround this restriction, this patchset adds a kernel cmdline
option to pick a default algorithm, skipping the performace tests.

That approach might cause some performance hit in RAID6 users (although GCP
reports that this is not common), but will reduce boot time and it can be
reverted to the original behaviour via a cmdline option.

I also proposed that we work with upstream to delay this algorithm performance
test until RAID6 is really required during the boot (eventually never being
needed). However that is a solution that would require more time to be
discussed, implemented and tested.

Marcelo Henrique Cerri (2):
  UBUNTU: SAUCE: raid6: Add option for default PQ algorithm
  UBUNTU: [config] linux-gcp: CONFIG_RAID6_PQ_DEFAULT_ALG="avx2x4"

 debian.gcp/config/config.common.ubuntu |  2 ++
 lib/Kconfig                            | 17 +++++++++++++++++
 lib/raid6/algos.c                      | 26 ++++++++++++++++++++++++++
 3 files changed, 45 insertions(+)


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