Commit 350dce38 authored by Hao Zhang's avatar Hao Zhang Committed by Andrew Morton
Browse files

mm/vmscan: extract calculated pressure balance as a function 

Extract pressure balance calculation into a function.This doesn't change
current behaviour.

[akpm@linux-foundation.org: 80-col wrapping]
Link: https://lkml.kernel.org/r/tencent_735DB36A2306C08B8568049E4C0B99716C07@qq.com


Signed-off-by: default avatarHao Zhang <zhanghao1@kylinos.cn>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent b8932ca8

mm/vmscan.c

+38 −30
Original line number Diff line number Diff line
@@ -2400,6 +2400,43 @@ static void prepare_scan_control(pg_data_t *pgdat, struct scan_control *sc) 
	}

}



static inline void calculate_pressure_balance(struct scan_control *sc,

			int swappiness, u64 *fraction, u64 *denominator)

{

	unsigned long anon_cost, file_cost, total_cost;

	unsigned long ap, fp;



	/*

	 * Calculate the pressure balance between anon and file pages.

	 *

	 * The amount of pressure we put on each LRU is inversely

	 * proportional to the cost of reclaiming each list, as

	 * determined by the share of pages that are refaulting, times

	 * the relative IO cost of bringing back a swapped out

	 * anonymous page vs reloading a filesystem page (swappiness).

	 *

	 * Although we limit that influence to ensure no list gets

	 * left behind completely: at least a third of the pressure is

	 * applied, before swappiness.

	 *

	 * With swappiness at 100, anon and file have equal IO cost.

	 */

	total_cost = sc->anon_cost + sc->file_cost;

	anon_cost = total_cost + sc->anon_cost;

	file_cost = total_cost + sc->file_cost;

	total_cost = anon_cost + file_cost;



	ap = swappiness * (total_cost + 1);

	ap /= anon_cost + 1;



	fp = (MAX_SWAPPINESS - swappiness) * (total_cost + 1);

	fp /= file_cost + 1;



	fraction[WORKINGSET_ANON] = ap;

	fraction[WORKINGSET_FILE] = fp;

	*denominator = ap + fp;

}



/*

 * Determine how aggressively the anon and file LRU lists should be

 * scanned.
@@ -2412,12 +2449,10 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, 
{

	struct pglist_data *pgdat = lruvec_pgdat(lruvec);

	struct mem_cgroup *memcg = lruvec_memcg(lruvec);

	unsigned long anon_cost, file_cost, total_cost;

	int swappiness = sc_swappiness(sc, memcg);

	u64 fraction[ANON_AND_FILE];

	u64 denominator = 0;	/* gcc */

	enum scan_balance scan_balance;

	unsigned long ap, fp;

	enum lru_list lru;



	/* If we have no swap space, do not bother scanning anon folios. */
@@ -2466,35 +2501,8 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, 
	}



	scan_balance = SCAN_FRACT;

	/*

	 * Calculate the pressure balance between anon and file pages.

	 *

	 * The amount of pressure we put on each LRU is inversely

	 * proportional to the cost of reclaiming each list, as

	 * determined by the share of pages that are refaulting, times

	 * the relative IO cost of bringing back a swapped out

	 * anonymous page vs reloading a filesystem page (swappiness).

	 *

	 * Although we limit that influence to ensure no list gets

	 * left behind completely: at least a third of the pressure is

	 * applied, before swappiness.

	 *

	 * With swappiness at 100, anon and file have equal IO cost.

	 */

	total_cost = sc->anon_cost + sc->file_cost;

	anon_cost = total_cost + sc->anon_cost;

	file_cost = total_cost + sc->file_cost;

	total_cost = anon_cost + file_cost;



	ap = swappiness * (total_cost + 1);

	ap /= anon_cost + 1;



	fp = (MAX_SWAPPINESS - swappiness) * (total_cost + 1);

	fp /= file_cost + 1;

	calculate_pressure_balance(sc, swappiness, fraction, &denominator);



	fraction[0] = ap;

	fraction[1] = fp;

	denominator = ap + fp;

out:

	for_each_evictable_lru(lru) {

		bool file = is_file_lru(lru);