Public bug reported:

SRU Justification:

[Impact]

In Ubuntu AMIs for x86 and Graviton based EC2 instances, the standard
Ubuntu AMI comes without IRQ moderation enabled for ENA, which for our
latest generation instances with networking heavy workloads is up to a
25% performance regression (i.e. NGINX in a load-balancing
configuration).


[Fix]


The mainline Linux kernel will now support IRQ moderation by default for ENA in 
the 6.9 kernel release via this patch: 
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/drivers/net/ethernet/amazon/ena?id=50d7a2660579889fba28b7e4543d4ce85aa2311b

[Test Plan]

AWS tested

[Where problems could occur]

By enabling adaptive coalescing, the default interrupt behaviour will by
changed to be more adaptive, which shows improvements on heavy network
workloads, but my change the behaviour and performance on other network
workloads differently.   Rather than handling the interrupts based off
of a fixed amount of time elapsed, it will change to an adaptive based
approach.   There should be no negative impact on light workloads, and a
positive impact on heavy work loads.  If there is an impact though, this
option can be disabled via the ethtool command.

[Other Info]

SF: 00380449

** Affects: linux-aws (Ubuntu)
     Importance: Undecided
     Assignee: Philip Cox (philcox)
         Status: In Progress

** Affects: linux-aws (Ubuntu Focal)
     Importance: Undecided
         Status: In Progress

** Affects: linux-aws (Ubuntu Jammy)
     Importance: Undecided
         Status: In Progress

** Affects: linux-aws (Ubuntu Mantic)
     Importance: Undecided
         Status: In Progress

** Affects: linux-aws (Ubuntu Noble)
     Importance: Undecided
     Assignee: Philip Cox (philcox)
         Status: In Progress

** Also affects: linux-aws (Ubuntu Jammy)
   Importance: Undecided
       Status: New

** Also affects: linux-aws (Ubuntu Noble)
   Importance: Undecided
     Assignee: Philip Cox (philcox)
       Status: New

** Also affects: linux-aws (Ubuntu Mantic)
   Importance: Undecided
       Status: New

** Also affects: linux-aws (Ubuntu Focal)
   Importance: Undecided
       Status: New

** Changed in: linux-aws (Ubuntu Jammy)
       Status: New => In Progress

** Changed in: linux-aws (Ubuntu Mantic)
       Status: New => In Progress

** Changed in: linux-aws (Ubuntu Focal)
       Status: New => In Progress

** Changed in: linux-aws (Ubuntu Noble)
       Status: New => In Progress

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https://bugs.launchpad.net/bugs/2056475

Title:
  aws: Backport latest ENA driver in upstream Linux to enable IRQ
  moderation

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