ACK: [SRU][G/aws][PATCH 0/2] aws: update patch to batch hibernate and resume IO requests

[William Breathitt Gray]

On Wed, Nov 04, 2020 at 01:05:52PM +0100, Andrea Righi wrote:
> BugLink: https://bugs.launchpad.net/bugs/1902864
> 
> [Impact]
> 
> During hibernation and resume the kernel is submitting an individual IO
> request for each page of data. In the aws kernel we are using a custom
> SAUCE patch to batch IO requests together in order to achieve better
> performance.
> 
> Recently a patch designed to achieve the same goal has been applied
> upstream. This patch has been acknowledged by Amazon and it has shown a
> performance improvement.
> 
> Moreover, this patch looks much cleaner compared to the custom patch
> that we are using and it's upstream, so it makes sense to drop the
> previous patch and apply this new one.
> 
> [Test case]
> 
> Hibernate + resume and measure the time required to perform these
> operations.
> 
> Performance result reported by Amazon:
> 
>     One hibernate and resume cycle for 16GB RAM out of 32GB in use takes
>     around 21 minutes before the change, and 1 minutes after the change on
>     a system with limited storage IOPS.
> 
> [Fix]
> 
> Apply the following upstream commit:
> 
>  55c4478a8f0ecedc0c1a0c9379380249985c372a ("PM: hibernate: Batch hibernate and resume IO requests")
> 
> Drop the custom aws SAUCE patch:
> 
>  11c3fa3b29722124f5c9122671983614383686db ("UBUNTU: SAUCE: [aws] PM / hibernate: Speed up hibernation by batching requests")
> 
> [Regression potential]
> 
> Upstream patch that allows to drop a custom patch that is doing the same
> thing. The only potential regression would be a performance drop, but
> according to Amazon's tests and our tests, we didn't notice any
> performance regression. Any other kind of regression would be considered
> as upstream regressions.
> 
> ----------------------------------------------------------------
> Andrea Righi (1):
>       Revert "UBUNTU: SAUCE: [aws] PM / hibernate: Speed up hibernation by batching requests"
> 
> Xiaoyi Chen (1):
>       PM: hibernate: Batch hibernate and resume IO requests
> 
>  kernel/power/swap.c | 250 ++++++++++------------------------------------------
>  1 file changed, 49 insertions(+), 201 deletions(-)

Always nice to replace a SAUCE with an upstream cherry-pick. :-)

Thanks!

Acked-by: William Breathitt Gray <william.gray at canonical.com>
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