Re: [PATCH 6/7] workqueue: Report work funcs that trigger automatic CPU_INTENSIVE mechanism

[Peter Zijlstra]

On Thu, May 11, 2023 at 08:19:30AM -1000, Tejun Heo wrote:
> Workqueue now automatically marks per-cpu work items that hog CPU for too
> long as CPU_INTENSIVE, which excludes them from concurrency management and
> prevents stalling other concurrency-managed work items. If a work function
> keeps running over the thershold, it likely needs to be switched to use an
> unbound workqueue.
> 
> This patch adds a debug mechanism which tracks the work functions which
> trigger the automatic CPU_INTENSIVE mechanism and report them using
> pr_warn() with exponential backoff.
> 
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

I did do wonder why you chose for external storage for this -- I figured
it was to keep the cost down since it shouldn't really be happening, so
storage in the normal data structures is a waste etc..?

Otherwise seems fine; thanks!