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mm: add free_unref_folios() 

Iterate over a folio_batch rather than a linked list.  This is easier for
the CPU to prefetch and has a batch count naturally built in so we don't
need to track it.  Again, this lowers the maximum lock hold time from
32 folios to 15, but I do not expect this to have a significant effect.

Link: https://lkml.kernel.org/r/20240227174254.710559-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2024-02-27 17:42:37 +00:00 committed by Andrew Morton
parent 7c76d92253
commit 90491d87dd
2 changed files with 39 additions and 25 deletions
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5
mm/internal.h
View File

@ -451,8 +451,9 @@ extern bool free_pages_prepare(struct page *page, unsigned int order);
extern int user_min_free_kbytes;
extern void free_unref_page(struct page *page, unsigned int order);
extern void free_unref_page_list(struct list_head *list);
void free_unref_page(struct page *page, unsigned int order);
void free_unref_folios(struct folio_batch *fbatch);
void free_unref_page_list(struct list_head *list);
extern void zone_pcp_reset(struct zone *zone);
extern void zone_pcp_disable(struct zone *zone);

59
mm/page_alloc.c
View File

@ -32,6 +32,7 @@
#include <linux/sysctl.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/pagevec.h>
#include <linux/memory_hotplug.h>
#include <linux/nodemask.h>
#include <linux/vmstat.h>
@ -2515,57 +2516,51 @@ void free_unref_page(struct page *page, unsigned int order)
}
/*
* Free a list of 0-order pages
* Free a batch of 0-order pages
*/
void free_unref_page_list(struct list_head *list)
void free_unref_folios(struct folio_batch *folios)
{
unsigned long __maybe_unused UP_flags;
struct folio *folio, *next;
struct per_cpu_pages *pcp = NULL;
struct zone *locked_zone = NULL;
int batch_count = 0;
int migratetype;
int i, j, migratetype;
/* Prepare pages for freeing */
list_for_each_entry_safe(folio, next, list, lru) {
/* Prepare folios for freeing */
for (i = 0, j = 0; i < folios->nr; i++) {
struct folio *folio = folios->folios[i];
unsigned long pfn = folio_pfn(folio);
if (!free_unref_page_prepare(&folio->page, pfn, 0)) {
list_del(&folio->lru);
if (!free_unref_page_prepare(&folio->page, pfn, 0))
continue;
}
/*
* Free isolated pages directly to the allocator, see
* Free isolated folios directly to the allocator, see
* comment in free_unref_page.
*/
migratetype = get_pcppage_migratetype(&folio->page);
if (unlikely(is_migrate_isolate(migratetype))) {
list_del(&folio->lru);
free_one_page(folio_zone(folio), &folio->page, pfn,
0, migratetype, FPI_NONE);
continue;
}
if (j != i)
folios->folios[j] = folio;
j++;
}
folios->nr = j;
list_for_each_entry_safe(folio, next, list, lru) {
for (i = 0; i < folios->nr; i++) {
struct folio *folio = folios->folios[i];
struct zone *zone = folio_zone(folio);
list_del(&folio->lru);
migratetype = get_pcppage_migratetype(&folio->page);
/*
* Either different zone requiring a different pcp lock or
* excessive lock hold times when freeing a large list of
* folios.
*/
if (zone != locked_zone || batch_count == SWAP_CLUSTER_MAX) {
/* Different zone requires a different pcp lock */
if (zone != locked_zone) {
if (pcp) {
pcp_spin_unlock(pcp);
pcp_trylock_finish(UP_flags);
}
batch_count = 0;
/*
* trylock is necessary as folios may be getting freed
* from IRQ or SoftIRQ context after an IO completion.
@ -2592,13 +2587,31 @@ void free_unref_page_list(struct list_head *list)
trace_mm_page_free_batched(&folio->page);
free_unref_page_commit(zone, pcp, &folio->page, migratetype, 0);
batch_count++;
}
if (pcp) {
pcp_spin_unlock(pcp);
pcp_trylock_finish(UP_flags);
}
folio_batch_reinit(folios);
}
void free_unref_page_list(struct list_head *list)
{
struct folio_batch fbatch;
folio_batch_init(&fbatch);
while (!list_empty(list)) {
struct folio *folio = list_first_entry(list, struct folio, lru);
list_del(&folio->lru);
if (folio_batch_add(&fbatch, folio) > 0)
continue;
free_unref_folios(&fbatch);
}
if (fbatch.nr)
free_unref_folios(&fbatch);
}
/*