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mm/compaction: optimize >0 order folio compaction with free page split. 

During migration in a memory compaction, free pages are placed in an array
of page lists based on their order.  But the desired free page order
(i.e., the order of a source page) might not be always present, thus
leading to migration failures and premature compaction termination.  Split
a high order free pages when source migration page has a lower order to
increase migration successful rate.

Note: merging free pages when a migration fails and a lower order free
page is returned via compaction_free() is possible, but there is too much
work.  Since the free pages are not buddy pages, it is hard to identify
these free pages using existing PFN-based page merging algorithm.

Link: https://lkml.kernel.org/r/20240220183220.1451315-5-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Adam Manzanares <a.manzanares@samsung.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Zi Yan 2024-02-20 13:32:20 -05:00 committed by Andrew Morton
parent 733aea0b3a
commit 73318e2caf
1 changed files with 30 additions and 5 deletions
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35
mm/compaction.c
View File

@ -1856,15 +1856,40 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data)
struct compact_control *cc = (struct compact_control *)data;
struct folio *dst;
int order = folio_order(src);
bool has_isolated_pages = false;
int start_order;
struct page *freepage;
unsigned long size;
if (list_empty(&cc->freepages[order])) {
isolate_freepages(cc);
if (list_empty(&cc->freepages[order]))
again:
for (start_order = order; start_order < NR_PAGE_ORDERS; start_order++)
if (!list_empty(&cc->freepages[start_order]))
break;
/* no free pages in the list */
if (start_order == NR_PAGE_ORDERS) {
if (has_isolated_pages)
return NULL;
isolate_freepages(cc);
has_isolated_pages = true;
goto again;
}
dst = list_first_entry(&cc->freepages[order], struct folio, lru);
list_del(&dst->lru);
freepage = list_first_entry(&cc->freepages[start_order], struct page,
lru);
size = 1 << start_order;
list_del(&freepage->lru);
while (start_order > order) {
start_order--;
size >>= 1;
list_add(&freepage[size].lru, &cc->freepages[start_order]);
set_page_private(&freepage[size], start_order);
}
dst = (struct folio *)freepage;
post_alloc_hook(&dst->page, order, __GFP_MOVABLE);
if (order)
prep_compound_page(&dst->page, order);