[PATCH 0/2][lunar/jammy linux-azure] Azure: MANA: Fix doorbell access for receives

Tim Gardner tim.gardner at canonical.com
Wed Jul 12 18:50:57 UTC 2023

BugLink: https://bugs.launchpad.net/bugs/2027615

SRU Justification


It's inefficient to ring the doorbell page every time a WQE is posted to
the received queue. Excessive MMIO writes result in CPU spending more
time waiting on LOCK instructions (atomic operations), resulting in
poor scaling performance.

[Test Plan]

MSFT tested. Performance improved substantially.

[Regression Potential]

The MANA receive queue could stop.

[Other Info]

SF: #00363437

These 2 patches have been submitted for upstream inclusion. I expect
them to eventually come down via stable updates.

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