From eb52286634f042432ec775077a73334603a1c6e4 Mon Sep 17 00:00:00 2001 From: "Gang Li Subject: padata: dispatch works on" Date: Wed, 6 Mar 2024 13:04:17 -0800 Subject: [PATCH] Author: Gang Li padata: dispatch works on different nodes Date: Thu, 22 Feb 2024 22:04:17 +0800 When a group of tasks that access different nodes are scheduled on the same node, they may encounter bandwidth bottlenecks and access latency. Thus, numa_aware flag is introduced here, allowing tasks to be distributed across different nodes to fully utilize the advantage of multi-node systems. Link: https://lkml.kernel.org/r/20240222140422.393911-5-gang.li@linux.dev Signed-off-by: Gang Li Tested-by: David Rientjes Reviewed-by: Muchun Song Reviewed-by: Tim Chen Cc: Alexey Dobriyan Cc: Daniel Jordan Cc: David Hildenbrand Cc: Jane Chu Cc: Mike Kravetz Cc: Paul E. McKenney Cc: Randy Dunlap Cc: Steffen Klassert Signed-off-by: Andrew Morton --- include/linux/padata.h | 2 ++ kernel/padata.c | 14 ++++++++++++-- mm/mm_init.c | 1 + 3 files changed, 15 insertions(+), 2 deletions(-) diff --git a/include/linux/padata.h b/include/linux/padata.h index 495b16b6b4d7..8f418711351b 100644 --- a/include/linux/padata.h +++ b/include/linux/padata.h @@ -137,6 +137,7 @@ struct padata_shell { * appropriate for one worker thread to do at once. * @max_threads: Max threads to use for the job, actual number may be less * depending on task size and minimum chunk size. + * @numa_aware: Distribute jobs to different nodes with CPU in a round robin fashion. */ struct padata_mt_job { void (*thread_fn)(unsigned long start, unsigned long end, void *arg); @@ -146,6 +147,7 @@ struct padata_mt_job { unsigned long align; unsigned long min_chunk; int max_threads; + bool numa_aware; }; /** diff --git a/kernel/padata.c b/kernel/padata.c index 179fb1518070..e3f639ff1670 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -485,7 +485,8 @@ void __init padata_do_multithreaded(struct padata_mt_job *job) struct padata_work my_work, *pw; struct padata_mt_job_state ps; LIST_HEAD(works); - int nworks; + int nworks, nid; + static atomic_t last_used_nid __initdata; if (job->size == 0) return; @@ -517,7 +518,16 @@ void __init padata_do_multithreaded(struct padata_mt_job *job) ps.chunk_size = roundup(ps.chunk_size, job->align); list_for_each_entry(pw, &works, pw_list) - queue_work(system_unbound_wq, &pw->pw_work); + if (job->numa_aware) { + int old_node = atomic_read(&last_used_nid); + + do { + nid = next_node_in(old_node, node_states[N_CPU]); + } while (!atomic_try_cmpxchg(&last_used_nid, &old_node, nid)); + queue_work_node(nid, system_unbound_wq, &pw->pw_work); + } else { + queue_work(system_unbound_wq, &pw->pw_work); + } /* Use the current thread, which saves starting a workqueue worker. */ padata_work_init(&my_work, padata_mt_helper, &ps, PADATA_WORK_ONSTACK); diff --git a/mm/mm_init.c b/mm/mm_init.c index 2c19f5515e36..549e76af8f82 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -2231,6 +2231,7 @@ static int __init deferred_init_memmap(void *data) .align = PAGES_PER_SECTION, .min_chunk = PAGES_PER_SECTION, .max_threads = max_threads, + .numa_aware = false, }; padata_do_multithreaded(&job);