mm: vmscan: clean up get_scan_count()
Reclaim pressure balance between anon and file pages is calculated through a tuple of numerators and a shared denominator. Exceptional cases that want to force-scan anon or file pages configure the numerators and denominator such that one list is preferred, which is not necessarily the most obvious way: fraction[0] = 1; fraction[1] = 0; denominator = 1; goto out; Make this easier by making the force-scan cases explicit and use the fractionals only in case they are calculated from reclaim history. [akpm@linux-foundation.org: avoid using unintialized_var()] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Satoru Moriya <satoru.moriya@hds.com> Cc: Simon Jeons <simon.jeons@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
11d16c25bb
commit
9a2651140e
65
mm/vmscan.c
65
mm/vmscan.c
|
@ -1638,6 +1638,13 @@ static int vmscan_swappiness(struct scan_control *sc)
|
|||
return mem_cgroup_swappiness(sc->target_mem_cgroup);
|
||||
}
|
||||
|
||||
enum scan_balance {
|
||||
SCAN_EQUAL,
|
||||
SCAN_FRACT,
|
||||
SCAN_ANON,
|
||||
SCAN_FILE,
|
||||
};
|
||||
|
||||
/*
|
||||
* Determine how aggressively the anon and file LRU lists should be
|
||||
* scanned. The relative value of each set of LRU lists is determined
|
||||
|
@ -1650,14 +1657,16 @@ static int vmscan_swappiness(struct scan_control *sc)
|
|||
static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
|
||||
unsigned long *nr)
|
||||
{
|
||||
unsigned long anon, file, free;
|
||||
unsigned long anon_prio, file_prio;
|
||||
unsigned long ap, fp;
|
||||
struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
|
||||
u64 fraction[2], denominator;
|
||||
enum lru_list lru;
|
||||
bool force_scan = false;
|
||||
u64 fraction[2];
|
||||
u64 denominator = 0; /* gcc */
|
||||
struct zone *zone = lruvec_zone(lruvec);
|
||||
unsigned long anon_prio, file_prio;
|
||||
enum scan_balance scan_balance;
|
||||
unsigned long anon, file, free;
|
||||
bool force_scan = false;
|
||||
unsigned long ap, fp;
|
||||
enum lru_list lru;
|
||||
|
||||
/*
|
||||
* If the zone or memcg is small, nr[l] can be 0. This
|
||||
|
@ -1676,9 +1685,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
|
|||
|
||||
/* If we have no swap space, do not bother scanning anon pages. */
|
||||
if (!sc->may_swap || (nr_swap_pages <= 0)) {
|
||||
fraction[0] = 0;
|
||||
fraction[1] = 1;
|
||||
denominator = 1;
|
||||
scan_balance = SCAN_FILE;
|
||||
goto out;
|
||||
}
|
||||
|
||||
|
@ -1690,9 +1697,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
|
|||
* too expensive.
|
||||
*/
|
||||
if (!global_reclaim(sc) && !vmscan_swappiness(sc)) {
|
||||
fraction[0] = 0;
|
||||
fraction[1] = 1;
|
||||
denominator = 1;
|
||||
scan_balance = SCAN_FILE;
|
||||
goto out;
|
||||
}
|
||||
|
||||
|
@ -1702,9 +1707,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
|
|||
* (unless the swappiness setting disagrees with swapping).
|
||||
*/
|
||||
if (!sc->priority && vmscan_swappiness(sc)) {
|
||||
fraction[0] = 1;
|
||||
fraction[1] = 1;
|
||||
denominator = 1;
|
||||
scan_balance = SCAN_EQUAL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
|
@ -1722,9 +1725,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
|
|||
if (global_reclaim(sc)) {
|
||||
free = zone_page_state(zone, NR_FREE_PAGES);
|
||||
if (unlikely(file + free <= high_wmark_pages(zone))) {
|
||||
fraction[0] = 1;
|
||||
fraction[1] = 0;
|
||||
denominator = 1;
|
||||
scan_balance = SCAN_ANON;
|
||||
goto out;
|
||||
}
|
||||
}
|
||||
|
@ -1734,12 +1735,12 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
|
|||
* anything from the anonymous working set right now.
|
||||
*/
|
||||
if (!inactive_file_is_low(lruvec)) {
|
||||
fraction[0] = 0;
|
||||
fraction[1] = 1;
|
||||
denominator = 1;
|
||||
scan_balance = SCAN_FILE;
|
||||
goto out;
|
||||
}
|
||||
|
||||
scan_balance = SCAN_FRACT;
|
||||
|
||||
/*
|
||||
* With swappiness at 100, anonymous and file have the same priority.
|
||||
* This scanning priority is essentially the inverse of IO cost.
|
||||
|
@ -1792,9 +1793,31 @@ out:
|
|||
|
||||
size = get_lru_size(lruvec, lru);
|
||||
scan = size >> sc->priority;
|
||||
|
||||
if (!scan && force_scan)
|
||||
scan = min(size, SWAP_CLUSTER_MAX);
|
||||
|
||||
switch (scan_balance) {
|
||||
case SCAN_EQUAL:
|
||||
/* Scan lists relative to size */
|
||||
break;
|
||||
case SCAN_FRACT:
|
||||
/*
|
||||
* Scan types proportional to swappiness and
|
||||
* their relative recent reclaim efficiency.
|
||||
*/
|
||||
scan = div64_u64(scan * fraction[file], denominator);
|
||||
break;
|
||||
case SCAN_FILE:
|
||||
case SCAN_ANON:
|
||||
/* Scan one type exclusively */
|
||||
if ((scan_balance == SCAN_FILE) != file)
|
||||
scan = 0;
|
||||
break;
|
||||
default:
|
||||
/* Look ma, no brain */
|
||||
BUG();
|
||||
}
|
||||
nr[lru] = scan;
|
||||
}
|
||||
}
|
||||
|
|
Loading…
Reference in New Issue