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

[Thadeu Lima de Souza Cascardo]

On Mon, Jan 21, 2019 at 04:55:29PM -0200, Marcelo Henrique Cerri wrote:
> 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(+)
> 
> -- 
> 2.17.1

While I would rather see something that goes upstream, as this is only applied
to GCP (for now), I am happy with the approach taken.

Acked-by: Thadeu Lima de Souza Cascardo <cascardo at canonical.com>