Re: [iwl-next PATCH v4 2/3] idpf: convert workqueues to unbound

[Alexander Lobakin]

From: Brian Vazquez <brianvv@xxxxxxxxxx>
Date: Mon, 16 Dec 2024 16:27:34 +0000

> From: Marco Leogrande <leogrande@xxxxxxxxxx>
> 
> When a workqueue is created with `WQ_UNBOUND`, its work items are
> served by special worker-pools, whose host workers are not bound to
> any specific CPU. In the default configuration (i.e. when
> `queue_delayed_work` and friends do not specify which CPU to run the
> work item on), `WQ_UNBOUND` allows the work item to be executed on any
> CPU in the same node of the CPU it was enqueued on. While this
> solution potentially sacrifices locality, it avoids contention with
> other processes that might dominate the CPU time of the processor the
> work item was scheduled on.
> 
> This is not just a theoretical problem: in a particular scenario
> misconfigured process was hogging most of the time from CPU0, leaving
> less than 0.5% of its CPU time to the kworker. The IDPF workqueues
> that were using the kworker on CPU0 suffered large completion delays
> as a result, causing performance degradation, timeouts and eventual
> system crash.

Wasn't this inspired by [0]?

[0]
https://lore.kernel.org/netdev/20241126035849.6441-11-milena.olech@xxxxxxxxx

Thanks,
Olek