Public bug reported:
[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
** Affects: linux (Ubuntu)
Importance: High
Assignee: Heitor Alves de Siqueira (halves)
Status: Confirmed
** Affects: linux (Ubuntu Focal)
Importance: Undecided
Status: New
** Affects: linux (Ubuntu Impish)
Importance: Undecided
Status: New
** Affects: linux (Ubuntu Jammy)
Importance: High
Assignee: Heitor Alves de Siqueira (halves)
Status: Confirmed
** Tags: sts
** Also affects: linux (Ubuntu Focal)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Jammy)
Importance: High
Assignee: Heitor Alves de Siqueira (halves)
Status: Confirmed
** Also affects: linux (Ubuntu Impish)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1964512
Title:
Low RX performance for 40G Solarflare NICs
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