Hi, I've identified several potential optimizations for padata. I'd appreciate it if you could take a look at my ideas to see if they are feasible. Utilizing the WQ_SYSFS from workqueue to support sysfs ====================================================== Padata relies on workqueue, and since workqueue has already implemented support for cpumask through WQ_SYSFS, we can reuse this functionality and avoid redundant implementation. Link: https://docs.kernel.org/core-api/workqueue.html#affinity-scopes Using completion to ensure the sequencing of the 'serial()' =========================================================== In the current implementation, to ensure the sequencing of 'serial()', we've used seq_nr, reorder_list, padata_serial_queue, reorder_work... which has made the logic quite complex. These operations can be simplified by using 'completion'. Specifically: 1. in padata_do_parallel() 1. init_completion(parallel_done) **before** queue_work 2. queue_work(serial_work) 2. in padata_parallel_worker 1. complete(parallel_done) **after** parallel(padata) 3. in padata_serial_worker 1. wait_for_completion(parallel_done) **before** serial(padata) Here's a simplified code snippet: ```c struct padata_priv { struct completion parallel_done; struct work_struct parallel_work; struct work_struct serial_work; void (*parallel)(struct padata_priv *padata); void (*serial)(struct padata_priv *padata); } void padata_do_parallel(struct padata_priv *padata) { ... init_completion(&padata->parallel_done); queue_work(pinst->serial_wq, &padata->serial_work); queue_work(pinst->parallel_wq, &padata->parallel_work); ... } static void padata_parallel_worker(struct work_struct *parallel_work) { struct padata_priv *padata = container_of(parallel_work, struct padata_priv, parallel_work); padata->parallel(padata); // notify serial_worker to do serial() complete(&padata->parallel_done); } static void padata_serial_worker(struct work_struct *serial_work) { struct padata_priv *padata = container_of(serial_work, struct padata_priv, serial_work); wait_for_completion(&padata->parallel_done); padata->serial(padata); } ```