linux-5.15/kcompactd() の変更点

• 追加された行はこの色です。
• 削除された行はこの色です。
• linux-5.15/kcompactd() へ行く。
• linux-5.15/kcompactd() の差分を削除

#author("2025-09-11T13:46:16+09:00","default:guest","guest")
#author("2025-09-11T13:47:08+09:00","default:guest","guest")
*参照元 [#g5f1b261]
#backlinks

*説明 [#u580f8e1]
-パス: [[linux-5.15/mm/compaction.c]]

-kcompactdのスレッドメイン関数


**引数 [#kc412fe3]
-void *p
--メモリノード。pg_data_t型のポインタを指定する。
--[[linux-5.15/pg_data_t]]


**返り値 [#h05b60fb]
-int
--意味はない。常に0。
--常に0、基本的に終了しないので意味は特に無い。


**参考 [#h9ea645c]


*実装 [#v0fcdc16]

 /*
  * The background compaction daemon, started as a kernel thread
  * from the init process.
  */
 static int kcompactd(void *p)
 {
 	pg_data_t *pgdat = (pg_data_t *)p;
 	struct task_struct *tsk = current;
 	long default_timeout = msecs_to_jiffies(HPAGE_FRAG_CHECK_INTERVAL_MSEC);
 	long timeout = default_timeout;
 
 	const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
 
 	if (!cpumask_empty(cpumask))
 		set_cpus_allowed_ptr(tsk, cpumask);
 
 	set_freezable();
 
-
--[[linux-5.15/pg_data_t]]
--[[linux-5.15/task_struct]]
--[[linux-5.15/msecs_to_jiffies()]]
--[[linux-5.15/cpumask]]
--[[linux-5.15/cpumask_of_node()]]
--[[linux-5.15/cpumask_empty()]]
--[[linux-5.15/set_cpus_allowed_ptr()]]
--[[linux-5.15/set_freezable()]]

 	pgdat->kcompactd_max_order = 0;
 	pgdat->kcompactd_highest_zoneidx = pgdat->nr_zones - 1;
 
 	while (!kthread_should_stop()) {
 		unsigned long pflags;
 
 		/*
 		 * Avoid the unnecessary wakeup for proactive compaction
 		 * when it is disabled.
 		 */
 		if (!sysctl_compaction_proactiveness)
 			timeout = MAX_SCHEDULE_TIMEOUT;
 		trace_mm_compaction_kcompactd_sleep(pgdat->node_id);
 		if (wait_event_freezable_timeout(pgdat->kcompactd_wait,
 			kcompactd_work_requested(pgdat), timeout) &&
 			!pgdat->proactive_compact_trigger) {
 
-
--[[linux-5.15/kthread_should_stop()]]
--[[linux-5.15/trace_mm_compaction_kcompactd_sleep()]]
--[[linux-5.15/wait_freezable_timeout()]]
--[[linux-5.15/kcompactd_work_requested()]]

 			psi_memstall_enter(&pflags);
 			kcompactd_do_work(pgdat);
 			psi_memstall_leave(&pflags);
 			/*
 			 * Reset the timeout value. The defer timeout from
 			 * proactive compaction is lost here but that is fine
 			 * as the condition of the zone changing substantionally
 			 * then carrying on with the previous defer interval is
 			 * not useful.
 			 */
 			timeout = default_timeout;
 			continue;
 		}
 
-
--[[linux-5.15/psi_memstall_enter()]]
--[[linux-5.15/kcompactd_do_work()]]
--[[linux-5.15/psi_memstall_leave()]]

 		/*
 		 * Start the proactive work with default timeout. Based
 		 * on the fragmentation score, this timeout is updated.
 		 */
 		timeout = default_timeout;
 		if (should_proactive_compact_node(pgdat)) {
 			unsigned int prev_score, score;
 
 			prev_score = fragmentation_score_node(pgdat);
 			proactive_compact_node(pgdat);
 			score = fragmentation_score_node(pgdat);
 			/*
 			 * Defer proactive compaction if the fragmentation
 			 * score did not go down i.e. no progress made.
 			 */
 			if (unlikely(score >= prev_score))
 				timeout =
 				   default_timeout << COMPACT_MAX_DEFER_SHIFT;
 		}
 		if (unlikely(pgdat->proactive_compact_trigger))
 			pgdat->proactive_compact_trigger = false;

-
--[[linux-5.15/should_proactive_compact_node()]]
--[[linux-5.15/fragmentation_score_node()]]
--[[linux-5.15/proactive_compact_node()]]
--[[linux-5.15/unlikely()]]

 	}
 
 	return 0;
 }


*コメント [#cbc2437f]