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

Khaled Elmously khalid.elmously at canonical.com
Fri Feb 1 03:11:36 UTC 2019


On 2019-01-21 16:55:29 , 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
> 
> 
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