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mm/vmscan: extract calculated pressure balance as a function

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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: Hao Zhang <zhanghao1@kylinos.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Hao Zhang
2025-01-15 09:58:29 +08:00
committed by Andrew Morton
parent b8932ca8b9
commit 350dce38eb
1 changed files with 38 additions and 30 deletions
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68
mm/vmscan.c
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@@ -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;
calculate_pressure_balance(sc, swappiness, fraction, &denominator);
ap = swappiness * (total_cost + 1);
ap /= anon_cost + 1;
fp = (MAX_SWAPPINESS - swappiness) * (total_cost + 1);
fp /= file_cost + 1;
fraction[0] = ap;
fraction[1] = fp;
denominator = ap + fp;
out:
for_each_evictable_lru(lru) {
bool file = is_file_lru(lru);