Messages in this thread | | | From | Sebastian Andrzej Siewior <> | Subject | [PATCH net-next 0/2] net: Use SMP threads for backlog NAPI (or optional). | Date | Fri, 29 Sep 2023 18:20:18 +0200 |
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The RPS code and "deferred skb free" both send IPI/ function call to a remote CPU in which a softirq is raised. This leads to a warning on PREEMPT_RT because raising softiqrs from function call led to undesired behaviour in the past. I had duct tape in RT for the "deferred skb free" and Wander Lairson Costa reported the RPS case.
Changes: - RFC…v1 https://lore.kernel.org/all/20230818092111.5d86e351@kernel.org
- Patch #2 has been removed. Removing the warning is still an option.
- There are two patches in the series: - Patch #1 always creates backlog threads - Patch #2 creates the backlog threads if requested at boot time, mandatory on PREEMPT_RT. So it is either or and I wanted to show how both look like.
- The kernel test robot reported a performance regression with loopback (stress-ng --udp X --udp-ops Y) against the RFC version. The regression is now avoided by using local-NAPI if backlog processing is requested on the local CPU.
Sebastian
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