linux-5.15/shrink_lruvec() の履歴(No.2)

• 履歴一覧
• 差分 を表示
• 現在との差分 を表示
• ソース を表示
• linux-5.15/shrink_lruvec() へ行く。
  • 1 (2025-09-11 (木) 19:44:09)
  • 2 (2025-09-11 (木) 20:03:58)

参照元†

• linux-5.15/shrink_node_memcgs()

説明†

• パス: linux-5.15/mm/vmscan.c

• FIXME: これは何？
  • 説明

引数†

• pg_data_t *pgdat
  • メモリノード。
  • linux-5.15/pg_data_t
• struct scan_control *sc
  • linux-5.15/scan_control

返り値†

• なし

参考†

実装†

static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
{
	unsigned long nr[NR_LRU_LISTS];
	unsigned long targets[NR_LRU_LISTS];
	unsigned long nr_to_scan;
	enum lru_list lru;
	unsigned long nr_reclaimed = 0;
	unsigned long nr_to_reclaim = sc->nr_to_reclaim;
	struct blk_plug plug;
	bool scan_adjusted;

	get_scan_count(lruvec, sc, nr);

	/* Record the original scan target for proportional adjustments later */
	memcpy(targets, nr, sizeof(nr));

• • linux-5.15/lru_list
  • linux-5.15/blk_plug
  • linux-5.15/get_scan_count()

	/*
	 * Global reclaiming within direct reclaim at DEF_PRIORITY is a normal
	 * event that can occur when there is little memory pressure e.g.
	 * multiple streaming readers/writers. Hence, we do not abort scanning
	 * when the requested number of pages are reclaimed when scanning at
	 * DEF_PRIORITY on the assumption that the fact we are direct
	 * reclaiming implies that kswapd is not keeping up and it is best to
	 * do a batch of work at once. For memcg reclaim one check is made to
	 * abort proportional reclaim if either the file or anon lru has already
	 * dropped to zero at the first pass.
	 */
	scan_adjusted = (!cgroup_reclaim(sc) && !current_is_kswapd() &&
			 sc->priority == DEF_PRIORITY);

	blk_start_plug(&plug);

• • linux-5.15/cgroup_reclaim()
  • linux-5.15/current_is_kswapd()
  • linux-5.15/blk_start_plug()

	while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
					nr[LRU_INACTIVE_FILE]) {
		unsigned long nr_anon, nr_file, percentage;
		unsigned long nr_scanned;

		for_each_evictable_lru(lru) {
			if (nr[lru]) {
				nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX);
				nr[lru] -= nr_to_scan;

				nr_reclaimed += shrink_list(lru, nr_to_scan,
							    lruvec, sc);
			}
		}

		cond_resched();

• • linux-5.15/for_each_evictable_lru()
  • linux-5.15/shrink_list()
  • linux-5.15/cond_resched()

		if (nr_reclaimed < nr_to_reclaim || scan_adjusted)
			continue;

		/*
		 * For kswapd and memcg, reclaim at least the number of pages
		 * requested. Ensure that the anon and file LRUs are scanned
		 * proportionally what was requested by get_scan_count(). We
		 * stop reclaiming one LRU and reduce the amount scanning
		 * proportional to the original scan target.
		 */
		nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE];
		nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON];

		/*
		 * It's just vindictive to attack the larger once the smaller
		 * has gone to zero.  And given the way we stop scanning the
		 * smaller below, this makes sure that we only make one nudge
		 * towards proportionality once we've got nr_to_reclaim.
		 */
		if (!nr_file || !nr_anon)
			break;

		if (nr_file > nr_anon) {
			unsigned long scan_target = targets[LRU_INACTIVE_ANON] +
						targets[LRU_ACTIVE_ANON] + 1;
			lru = LRU_BASE;
			percentage = nr_anon * 100 / scan_target;
		} else {
			unsigned long scan_target = targets[LRU_INACTIVE_FILE] +
						targets[LRU_ACTIVE_FILE] + 1;
			lru = LRU_FILE;
			percentage = nr_file * 100 / scan_target;
		}

		/* Stop scanning the smaller of the LRU */
		nr[lru] = 0;
		nr[lru + LRU_ACTIVE] = 0;

		/*
		 * Recalculate the other LRU scan count based on its original
		 * scan target and the percentage scanning already complete
		 */
		lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE;
		nr_scanned = targets[lru] - nr[lru];
		nr[lru] = targets[lru] * (100 - percentage) / 100;
		nr[lru] -= min(nr[lru], nr_scanned);

		lru += LRU_ACTIVE;
		nr_scanned = targets[lru] - nr[lru];
		nr[lru] = targets[lru] * (100 - percentage) / 100;
		nr[lru] -= min(nr[lru], nr_scanned);

		scan_adjusted = true;
	}
	blk_finish_plug(&plug);
	sc->nr_reclaimed += nr_reclaimed;

• • linux-5.15/blk_finish_plug()

	/*
	 * Even if we did not try to evict anon pages at all, we want to
	 * rebalance the anon lru active/inactive ratio.
	 */
	if (can_age_anon_pages(lruvec_pgdat(lruvec), sc) &&
	    inactive_is_low(lruvec, LRU_INACTIVE_ANON))
		shrink_active_list(SWAP_CLUSTER_MAX, lruvec,
				   sc, LRU_ACTIVE_ANON);
}

• • linux-5.15/can_age_anon_pages()
  • linux-5.15/lruvec_pgdat()
  • linux-5.15/inactive_is_low()
  • linux-5.15/shrink_active_list()

コメント†