APPLIED: [PATCH 0/1][SRU][F/I] UBUNTU: SAUCE: sfc: The size of the RX recycle ring should be more flexible

[Stefan Bader]

On 10.03.22 21:44, Heitor Alves de Siqueira wrote:
> Buglink: https://bugs.launchpad.net/bugs/1964512
> 
> Hi kernel-team,
> 
> This patch is currently in net-next, and has not been merged into mainline yet.
> It's unlikely to make it into mainline before our next merge window, so I'm
> sending it for review as a SAUCE patch as some users have reported a huge impact
> on performance. We've provided backports for these users to test in bionic-hwe
> and focal-hwe, and they've reported it fixes their performance issues as
> expected.
> 
> Cheers,
> Heitor
> 
> [Backport Notes]
> * Clean cherry-pick for Jammy and Impish
> * Focal requires minor changes, as ef100 support was introduced in v5.9
> 
> [Impact]
> * Some 40G Solarflare NICs have low RX performance in some cases, due
>    low RX recycle ring size
> * RX recycle ring size is either 4096 for IOMMU, 16 for NOIOMMU
> * The low fixed sizes can cause a high number of calls to alloc_pages,
>    tanking performance for higher link speeds
> 
> [Test Plan]
> * Users report that iperf3 is sufficient to showcase the bad RX performance
> * For some setups, RX performance was around 15Gbps while TX stayed
>    consistently above 30Gbps
> 
> [Fix]
> * This patch sets the RX recycle ring size according to an adapter's
>    maximum link speed
> * Fix was introduced by commit:
>    000fe940e51f "sfc: The size of the RX recycle ring should be more flexible"
> * --!-- Commit is from net-next --!--
> 
> [Regression Potential]
> * Regressions would show primarily as performance issues, as we're
>    effectively changing ring sizes for all RX traffic
> * It's possible to see increased calls to alloc_pages if ring sizes
>    aren't being set correctly
> * We should look out for excessive memory usage in the sfc driver due to
>    the increased ring sizes
> 
> Martin Habets (1):
>    sfc: The size of the RX recycle ring should be more flexible
> 
>   drivers/net/ethernet/sfc/ef10.c       | 26 ++++++++++++++++++++++++++
>   drivers/net/ethernet/sfc/ef100_nic.c  |  9 +++++++++
>   drivers/net/ethernet/sfc/net_driver.h |  2 ++
>   drivers/net/ethernet/sfc/nic_common.h |  5 +++++
>   drivers/net/ethernet/sfc/rx_common.c  | 18 +-----------------
>   drivers/net/ethernet/sfc/rx_common.h  |  6 ++++++
>   drivers/net/ethernet/sfc/siena.c      |  8 ++++++++
>   7 files changed, 57 insertions(+), 17 deletions(-)
> 

Applied to impish,focal:linux/master-next. Thanks.

-Stefan

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