From: Zi Yan <[email protected]>
Hi all,
This patchset enables >0 order folio memory compaction, which is one of
the prerequisitions for large folio support[1]. It is on top of
mm-everything-2024-02-10-00-56.
I am aware of that split free pages is necessary for folio
migration in compaction, since if >0 order free pages are never split
and no order-0 free page is scanned, compaction will end prematurely due
to migration returns -ENOMEM. Free page split becomes a must instead of
an optimization.
lkp ncompare results (on a 8-CPU (Intel Xeon E5-2650 v4 @2.20GHz) 16G VM)
for default LRU (-no-mglru) and CONFIG_LRU_GEN are shown at the bottom,
copied from V3[4], since V4 is only a code refactoring of V3.
In sum, most of vm-scalability applications do not see performance
change, and the others see ~4% to ~26% performance boost under default LRU
and ~2% to ~6% performance boost under CONFIG_LRU_GEN.
Changelog
===
From V3 [4]:
1. Restructured isolate_migratepages_block() to minimize PageHuge() use
in Patch 1 (per Vlastimil Babka).
2. Used folio_put_testzero() instead of folio_set_count() to properly
handle free pages in compaction_free() (per Vlastimil Babka).
3. Simplified code to use struct list_head instead of a new struct page_list
(per Vlastimil Babka).
4. Restructured compaction_alloc() code to reduce indentation and
increase readability (per Vlastimil Babka).
From V2 [3]:
1. Added missing free page count in fast isolation path. This fixed the
weird performance outcome.
From V1 [2]:
1. Used folio_test_large() instead of folio_order() > 0. (per Matthew
Wilcox)
2. Fixed code rebase error. (per Baolin Wang)
3. Used list_split_init() instead of list_split(). (per Ryan Boberts)
4. Added free_pages_prepare_fpi_none() to avoid duplicate free page code
in compaction_free().
5. Dropped source page order sorting patch.
From RFC [1]:
1. Enabled >0 order folio compaction in the first patch by splitting all
to-be-migrated folios. (per Huang, Ying)
2. Stopped isolating compound pages with order greater than cc->order
to avoid wasting effort, since cc->order gives a hint that no free pages
with order greater than it exist, thus migrating the compound pages will fail.
(per Baolin Wang)
3. Retained the folio check within lru lock. (per Baolin Wang)
4. Made isolate_freepages_block() generate order-sorted multi lists.
(per Johannes Weiner)
Overview
===
To support >0 order folio compaction, the patchset changes how free pages used
for migration are kept during compaction. Free pages used to be split into
order-0 pages that are post allocation processed (i.e., PageBuddy flag cleared,
page order stored in page->private is zeroed, and page reference is set to 1).
Now all free pages are kept in a MAX_ORDER+1 array of page lists based
on their order without post allocation process. When migrate_pages() asks for
a new page, one of the free pages, based on the requested page order, is
then processed and given out.
Feel free to give comments and ask questions.
Thanks.
[1] https://lore.kernel.org/linux-mm/[email protected]/
[2] https://lore.kernel.org/linux-mm/[email protected]/
[3] https://lore.kernel.org/linux-mm/[email protected]/
[4] https://lore.kernel.org/linux-mm/[email protected]/
Hi Andrew,
Baolin's patch on nr_migratepages was based on this one, a better fixup
for it might be below. Since before my patchset, compaction only deals with
order-0 pages.
diff --git a/mm/compaction.c b/mm/compaction.c
index 01ec85cfd623f..e60135e2019d6 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1798,7 +1798,7 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data)
dst = list_entry(cc->freepages.next, struct folio, lru);
list_del(&dst->lru);
cc->nr_freepages--;
- cc->nr_migratepages -= 1 << order;
+ cc->nr_migratepages--;
return dst;
}
@@ -1814,7 +1814,7 @@ static void compaction_free(struct folio *dst, unsigned long data)
list_add(&dst->lru, &cc->freepages);
cc->nr_freepages++;
- cc->nr_migratepages += 1 << order;
+ cc->nr_migratepages++;
}
vm-scalability results on CONFIG_LRU_GEN
===
=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/mmap-xread-seq-mt/vm-scalability
commit:
6.8.0-rc1-mm-everything-2024-01-29-07-19+
6.8.0-rc1-split-folio-in-compaction+
6.8.0-rc1-folio-migration-in-compaction+
6.8.0-rc1-folio-migration-free-page-split+
6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
---------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \
15107616 +3.2% 15590339 +1.3% 15297619 +3.0% 15567998 vm-scalability.throughput
=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/mmap-pread-seq/vm-scalability
commit:
6.8.0-rc1-mm-everything-2024-01-29-07-19+
6.8.0-rc1-split-folio-in-compaction+
6.8.0-rc1-folio-migration-in-compaction+
6.8.0-rc1-folio-migration-free-page-split+
6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
---------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \
12611785 +1.8% 12832919 +0.9% 12724223 +1.6% 12812682 vm-scalability.throughput
=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/lru-file-readtwice/vm-scalability
commit:
6.8.0-rc1-mm-everything-2024-01-29-07-19+
6.8.0-rc1-split-folio-in-compaction+
6.8.0-rc1-folio-migration-in-compaction+
6.8.0-rc1-folio-migration-free-page-split+
6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
---------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \
9833393 +5.7% 10390190 +3.0% 10126606 +5.9% 10408804 vm-scalability.throughput
=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/lru-file-mmap-read/vm-scalability
commit:
6.8.0-rc1-mm-everything-2024-01-29-07-19+
6.8.0-rc1-split-folio-in-compaction+
6.8.0-rc1-folio-migration-in-compaction+
6.8.0-rc1-folio-migration-free-page-split+
6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
---------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \
7034709 ± 3% +2.9% 7241429 +3.2% 7256680 ± 2% +3.9% 7308375 vm-scalability.throughput
vm-scalability results on default LRU (with -no-mglru suffix)
===
=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/mmap-xread-seq-mt/vm-scalability
commit:
6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
6.8.0-rc1-split-folio-in-compaction-no-mglru+
6.8.0-rc1-folio-migration-in-compaction-no-mglru+
6.8.0-rc1-folio-migration-free-page-split-no-mglru+
6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
---------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \
14401491 +3.7% 14940270 +2.4% 14748626 +4.0% 14975716 vm-scalability.throughput
=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/mmap-pread-seq/vm-scalability
commit:
6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
6.8.0-rc1-split-folio-in-compaction-no-mglru+
6.8.0-rc1-folio-migration-in-compaction-no-mglru+
6.8.0-rc1-folio-migration-free-page-split-no-mglru+
6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
---------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \
11407497 +5.1% 11989632 -0.5% 11349272 +4.8% 11957423 vm-scalability.throughput
=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/mmap-pread-seq-mt/vm-scalability
commit:
6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
6.8.0-rc1-split-folio-in-compaction-no-mglru+
6.8.0-rc1-folio-migration-in-compaction-no-mglru+
6.8.0-rc1-folio-migration-free-page-split-no-mglru+
6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
---------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \
11348474 +3.3% 11719453 -1.2% 11208759 +3.7% 11771926 vm-scalability.throughput
=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/lru-file-readtwice/vm-scalability
commit:
6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
6.8.0-rc1-split-folio-in-compaction-no-mglru+
6.8.0-rc1-folio-migration-in-compaction-no-mglru+
6.8.0-rc1-folio-migration-free-page-split-no-mglru+
6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
---------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \
8065614 ± 3% +7.7% 8686626 ± 2% +5.0% 8467577 ± 4% +11.8% 9016077 ± 2% vm-scalability.throughput
=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/lru-file-mmap-read/vm-scalability
commit:
6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
6.8.0-rc1-split-folio-in-compaction-no-mglru+
6.8.0-rc1-folio-migration-in-compaction-no-mglru+
6.8.0-rc1-folio-migration-free-page-split-no-mglru+
6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
---------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \
6438422 ± 2% +27.5% 8206734 ± 2% +10.6% 7118390 +26.2% 8127192 ± 4% vm-scalability.throughput
Zi Yan (3):
mm/compaction: enable compacting >0 order folios.
mm/compaction: add support for >0 order folio memory compaction.
mm/compaction: optimize >0 order folio compaction with free page
split.
mm/compaction.c | 229 +++++++++++++++++++++++++++++++++---------------
mm/internal.h | 4 +-
mm/page_alloc.c | 6 ++
3 files changed, 166 insertions(+), 73 deletions(-)
--
2.43.0
From: Zi Yan <[email protected]>
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.
Signed-off-by: Zi Yan <[email protected]>
Reviewed-by: Baolin Wang <[email protected]>
Tested-by: Baolin Wang <[email protected]>
Cc: Adam Manzanares <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kemeng Shi <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Vishal Moola (Oracle) <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Yin Fengwei <[email protected]>
Cc: Yu Zhao <[email protected]>
---
mm/compaction.c | 36 +++++++++++++++++++++++++++++++-----
1 file changed, 31 insertions(+), 5 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index d0a05a621b67..25908e36b97c 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1832,15 +1832,41 @@ 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;
+
+again:
+ for (start_order = order; start_order < NR_PAGE_ORDERS; start_order++)
+ if (!list_empty(&cc->freepages[start_order]))
+ break;
- if (list_empty(&cc->freepages[order])) {
- isolate_freepages(cc);
- if (list_empty(&cc->freepages[order]))
+ /* no free pages in the list */
+ if (start_order == NR_PAGE_ORDERS) {
+ if (!has_isolated_pages) {
+ isolate_freepages(cc);
+ has_isolated_pages = true;
+ goto again;
+ } else
return NULL;
}
- 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);
--
2.43.0
From: Zi Yan <[email protected]>
Before last commit, memory compaction only migrates order-0 folios and
skips >0 order folios. Last commit splits all >0 order folios during
compaction. This commit migrates >0 order folios during compaction by
keeping isolated free pages at their original size without splitting them
into order-0 pages and using them directly during migration process.
What is different from the prior implementation:
1. All isolated free pages are kept in a NR_PAGE_ORDERS array of page
lists, where each page list stores free pages in the same order.
2. All free pages are not post_alloc_hook() processed nor buddy pages,
although their orders are stored in first page's private like buddy
pages.
3. During migration, in new page allocation time (i.e., in
compaction_alloc()), free pages are then processed by post_alloc_hook().
When migration fails and a new page is returned (i.e., in
compaction_free()), free pages are restored by reversing the
post_alloc_hook() operations using newly added
free_pages_prepare_fpi_none().
Step 3 is done for a latter optimization that splitting and/or merging
free pages during compaction becomes easier.
Note: without splitting free pages, compaction can end prematurely due to
migration will return -ENOMEM even if there is free pages. This happens
when no order-0 free page exist and compaction_alloc() return NULL.
Signed-off-by: Zi Yan <[email protected]>
Reviewed-by: Baolin Wang <[email protected]>
Tested-by: Baolin Wang <[email protected]>
Cc: Adam Manzanares <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kemeng Shi <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Vishal Moola (Oracle) <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Yin Fengwei <[email protected]>
Cc: Yu Zhao <[email protected]>
---
mm/compaction.c | 143 +++++++++++++++++++++++++++---------------------
mm/internal.h | 4 +-
mm/page_alloc.c | 6 ++
3 files changed, 91 insertions(+), 62 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index aa6aad805c4d..d0a05a621b67 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -66,45 +66,56 @@ static inline void count_compact_events(enum vm_event_item item, long delta)
#define COMPACTION_HPAGE_ORDER (PMD_SHIFT - PAGE_SHIFT)
#endif
-static unsigned long release_freepages(struct list_head *freelist)
+static void split_map_pages(struct list_head *freepages)
{
+ unsigned int i, order;
struct page *page, *next;
- unsigned long high_pfn = 0;
+ LIST_HEAD(tmp_list);
- list_for_each_entry_safe(page, next, freelist, lru) {
- unsigned long pfn = page_to_pfn(page);
- list_del(&page->lru);
- __free_page(page);
- if (pfn > high_pfn)
- high_pfn = pfn;
- }
+ for (order = 0; order < NR_PAGE_ORDERS; order++) {
+ list_for_each_entry_safe(page, next, &freepages[order], lru) {
+ unsigned int nr_pages;
- return high_pfn;
+ list_del(&page->lru);
+
+ nr_pages = 1 << order;
+
+ post_alloc_hook(page, order, __GFP_MOVABLE);
+ if (order)
+ split_page(page, order);
+
+ for (i = 0; i < nr_pages; i++) {
+ list_add(&page->lru, &tmp_list);
+ page++;
+ }
+ }
+ list_splice_init(&tmp_list, &freepages[0]);
+ }
}
-static void split_map_pages(struct list_head *list)
+static unsigned long release_free_list(struct list_head *freepages)
{
- unsigned int i, order, nr_pages;
- struct page *page, *next;
- LIST_HEAD(tmp_list);
-
- list_for_each_entry_safe(page, next, list, lru) {
- list_del(&page->lru);
+ int order;
+ unsigned long high_pfn = 0;
- order = page_private(page);
- nr_pages = 1 << order;
+ for (order = 0; order < NR_PAGE_ORDERS; order++) {
+ struct page *page, *next;
- post_alloc_hook(page, order, __GFP_MOVABLE);
- if (order)
- split_page(page, order);
+ list_for_each_entry_safe(page, next, &freepages[order], lru) {
+ unsigned long pfn = page_to_pfn(page);
- for (i = 0; i < nr_pages; i++) {
- list_add(&page->lru, &tmp_list);
- page++;
+ list_del(&page->lru);
+ /*
+ * Convert free pages into post allocation pages, so
+ * that we can free them via __free_page.
+ */
+ post_alloc_hook(page, order, __GFP_MOVABLE);
+ __free_pages(page, order);
+ if (pfn > high_pfn)
+ high_pfn = pfn;
}
}
-
- list_splice(&tmp_list, list);
+ return high_pfn;
}
#ifdef CONFIG_COMPACTION
@@ -657,7 +668,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
nr_scanned += isolated - 1;
total_isolated += isolated;
cc->nr_freepages += isolated;
- list_add_tail(&page->lru, freelist);
+ list_add_tail(&page->lru, &freelist[order]);
if (!strict && cc->nr_migratepages <= cc->nr_freepages) {
blockpfn += isolated;
@@ -722,7 +733,11 @@ isolate_freepages_range(struct compact_control *cc,
unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long isolated, pfn, block_start_pfn, block_end_pfn;
- LIST_HEAD(freelist);
+ int order;
+ struct list_head tmp_freepages[NR_PAGE_ORDERS];
+
+ for (order = 0; order < NR_PAGE_ORDERS; order++)
+ INIT_LIST_HEAD(&tmp_freepages[order]);
pfn = start_pfn;
block_start_pfn = pageblock_start_pfn(pfn);
@@ -753,7 +768,7 @@ isolate_freepages_range(struct compact_control *cc,
break;
isolated = isolate_freepages_block(cc, &isolate_start_pfn,
- block_end_pfn, &freelist, 0, true);
+ block_end_pfn, tmp_freepages, 0, true);
/*
* In strict mode, isolate_freepages_block() returns 0 if
@@ -770,15 +785,15 @@ isolate_freepages_range(struct compact_control *cc,
*/
}
- /* __isolate_free_page() does not map the pages */
- split_map_pages(&freelist);
-
if (pfn < end_pfn) {
/* Loop terminated early, cleanup. */
- release_freepages(&freelist);
+ release_free_list(tmp_freepages);
return 0;
}
+ /* __isolate_free_page() does not map the pages */
+ split_map_pages(tmp_freepages);
+
/* We don't use freelists for anything. */
return pfn;
}
@@ -1494,7 +1509,7 @@ fast_isolate_around(struct compact_control *cc, unsigned long pfn)
if (!page)
return;
- isolate_freepages_block(cc, &start_pfn, end_pfn, &cc->freepages, 1, false);
+ isolate_freepages_block(cc, &start_pfn, end_pfn, cc->freepages, 1, false);
/* Skip this pageblock in the future as it's full or nearly full */
if (start_pfn == end_pfn && !cc->no_set_skip_hint)
@@ -1623,7 +1638,7 @@ static void fast_isolate_freepages(struct compact_control *cc)
nr_scanned += nr_isolated - 1;
total_isolated += nr_isolated;
cc->nr_freepages += nr_isolated;
- list_add_tail(&page->lru, &cc->freepages);
+ list_add_tail(&page->lru, &cc->freepages[order]);
count_compact_events(COMPACTISOLATED, nr_isolated);
} else {
/* If isolation fails, abort the search */
@@ -1700,13 +1715,12 @@ static void isolate_freepages(struct compact_control *cc)
unsigned long isolate_start_pfn; /* exact pfn we start at */
unsigned long block_end_pfn; /* end of current pageblock */
unsigned long low_pfn; /* lowest pfn scanner is able to scan */
- struct list_head *freelist = &cc->freepages;
unsigned int stride;
/* Try a small search of the free lists for a candidate */
fast_isolate_freepages(cc);
if (cc->nr_freepages)
- goto splitmap;
+ return;
/*
* Initialise the free scanner. The starting point is where we last
@@ -1766,7 +1780,7 @@ static void isolate_freepages(struct compact_control *cc)
/* Found a block suitable for isolating free pages from. */
nr_isolated = isolate_freepages_block(cc, &isolate_start_pfn,
- block_end_pfn, freelist, stride, false);
+ block_end_pfn, cc->freepages, stride, false);
/* Update the skip hint if the full pageblock was scanned */
if (isolate_start_pfn == block_end_pfn)
@@ -1807,10 +1821,6 @@ static void isolate_freepages(struct compact_control *cc)
* and the loop terminated due to isolate_start_pfn < low_pfn
*/
cc->free_pfn = isolate_start_pfn;
-
-splitmap:
- /* __isolate_free_page() does not map the pages */
- split_map_pages(freelist);
}
/*
@@ -1821,24 +1831,22 @@ 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);
- /* this makes migrate_pages() split the source page and retry */
- if (folio_test_large(src) > 0)
- return NULL;
-
- if (list_empty(&cc->freepages)) {
+ if (list_empty(&cc->freepages[order])) {
isolate_freepages(cc);
-
- if (list_empty(&cc->freepages))
+ if (list_empty(&cc->freepages[order]))
return NULL;
}
- dst = list_entry(cc->freepages.next, struct folio, lru);
+ dst = list_first_entry(&cc->freepages[order], struct folio, lru);
list_del(&dst->lru);
- cc->nr_freepages--;
- cc->nr_migratepages -= 1 << folio_order(src);
-
- return dst;
+ post_alloc_hook(&dst->page, order, __GFP_MOVABLE);
+ if (order)
+ prep_compound_page(&dst->page, order);
+ cc->nr_freepages -= 1 << order;
+ cc->nr_migratepages -= 1 << order;
+ return page_rmappable_folio(&dst->page);
}
/*
@@ -1849,10 +1857,22 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data)
static void compaction_free(struct folio *dst, unsigned long data)
{
struct compact_control *cc = (struct compact_control *)data;
+ int order = folio_order(dst);
+ struct page *page = &dst->page;
+
+ if (folio_put_testzero(dst)) {
+ free_pages_prepare_fpi_none(page, order);
+
+ INIT_LIST_HEAD(&dst->lru);
- list_add(&dst->lru, &cc->freepages);
- cc->nr_freepages++;
- cc->nr_migratepages += 1 << folio_order(dst);
+ list_add(&dst->lru, &cc->freepages[order]);
+ cc->nr_freepages += 1 << order;
+ cc->nr_migratepages += 1 << order;
+ }
+ /*
+ * someone else has referenced the page, we cannot take it back to our
+ * free list.
+ */
}
/* possible outcome of isolate_migratepages */
@@ -2476,6 +2496,7 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
const bool sync = cc->mode != MIGRATE_ASYNC;
bool update_cached;
unsigned int nr_succeeded = 0;
+ int order;
/*
* These counters track activities during zone compaction. Initialize
@@ -2485,7 +2506,8 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
cc->total_free_scanned = 0;
cc->nr_migratepages = 0;
cc->nr_freepages = 0;
- INIT_LIST_HEAD(&cc->freepages);
+ for (order = 0; order < NR_PAGE_ORDERS; order++)
+ INIT_LIST_HEAD(&cc->freepages[order]);
INIT_LIST_HEAD(&cc->migratepages);
cc->migratetype = gfp_migratetype(cc->gfp_mask);
@@ -2671,7 +2693,7 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
* so we don't leave any returned pages behind in the next attempt.
*/
if (cc->nr_freepages > 0) {
- unsigned long free_pfn = release_freepages(&cc->freepages);
+ unsigned long free_pfn = release_free_list(cc->freepages);
cc->nr_freepages = 0;
VM_BUG_ON(free_pfn == 0);
@@ -2690,7 +2712,6 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
trace_mm_compaction_end(cc, start_pfn, end_pfn, sync, ret);
- VM_BUG_ON(!list_empty(&cc->freepages));
VM_BUG_ON(!list_empty(&cc->migratepages));
return ret;
diff --git a/mm/internal.h b/mm/internal.h
index 1e29c5821a1d..9925291e7704 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -447,6 +447,8 @@ extern void prep_compound_page(struct page *page, unsigned int order);
extern void post_alloc_hook(struct page *page, unsigned int order,
gfp_t gfp_flags);
+extern bool free_pages_prepare_fpi_none(struct page *page, unsigned int order);
+
extern int user_min_free_kbytes;
extern void free_unref_page(struct page *page, unsigned int order);
@@ -481,7 +483,7 @@ int split_free_page(struct page *free_page,
* completes when free_pfn <= migrate_pfn
*/
struct compact_control {
- struct list_head freepages; /* List of free pages to migrate to */
+ struct list_head freepages[NR_PAGE_ORDERS]; /* List of free pages to migrate to */
struct list_head migratepages; /* List of pages being migrated */
unsigned int nr_freepages; /* Number of isolated free pages */
unsigned int nr_migratepages; /* Number of pages to migrate */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7ae4b74c9e5c..e6e2ac722a82 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1179,6 +1179,12 @@ static __always_inline bool free_pages_prepare(struct page *page,
return true;
}
+__always_inline bool free_pages_prepare_fpi_none(struct page *page,
+ unsigned int order)
+{
+ return free_pages_prepare(page, order, FPI_NONE);
+}
+
/*
* Frees a number of pages from the PCP lists
* Assumes all pages on list are in same zone.
--
2.43.0
From: Zi Yan <[email protected]>
migrate_pages() supports >0 order folio migration and during compaction,
even if compaction_alloc() cannot provide >0 order free pages,
migrate_pages() can split the source page and try to migrate the base
pages from the split. It can be a baseline and start point for adding
support for compacting >0 order folios.
Signed-off-by: Zi Yan <[email protected]>
Suggested-by: Huang Ying <[email protected]>
Reviewed-by: Baolin Wang <[email protected]>
Tested-by: Baolin Wang <[email protected]>
Cc: Adam Manzanares <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kemeng Shi <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Vishal Moola (Oracle) <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Yin Fengwei <[email protected]>
Cc: Yu Zhao <[email protected]>
---
mm/compaction.c | 66 ++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 52 insertions(+), 14 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index cc801ce099b4..aa6aad805c4d 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -816,6 +816,21 @@ static bool too_many_isolated(struct compact_control *cc)
return too_many;
}
+/*
+ * 1. if the page order is larger than or equal to target_order (i.e.,
+ * cc->order and when it is not -1 for global compaction), skip it since
+ * target_order already indicates no free page with larger than target_order
+ * exists and later migrating it will most likely fail;
+ *
+ * 2. compacting > pageblock_order pages does not improve memory fragmentation,
+ * skip them;
+ */
+static bool skip_isolation_on_order(int order, int target_order)
+{
+ return (target_order != -1 && order >= target_order) ||
+ order >= pageblock_order;
+}
+
/**
* isolate_migratepages_block() - isolate all migrate-able pages within
* a single pageblock
@@ -947,7 +962,22 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
valid_page = page;
}
- if (PageHuge(page) && cc->alloc_contig) {
+ if (PageHuge(page)) {
+ /*
+ * skip hugetlbfs if we are not compacting for pages
+ * bigger than its order. THPs and other compound pages
+ * are handled below.
+ */
+ if (!cc->alloc_contig) {
+ const unsigned int order = compound_order(page);
+
+ if (order <= MAX_PAGE_ORDER) {
+ low_pfn += (1UL << order) - 1;
+ nr_scanned += (1UL << order) - 1;
+ }
+ goto isolate_fail;
+ }
+ /* for alloc_contig case */
if (locked) {
unlock_page_lruvec_irqrestore(locked, flags);
locked = NULL;
@@ -1008,21 +1038,24 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
}
/*
- * Regardless of being on LRU, compound pages such as THP and
- * hugetlbfs are not to be compacted unless we are attempting
- * an allocation much larger than the huge page size (eg CMA).
- * We can potentially save a lot of iterations if we skip them
- * at once. The check is racy, but we can consider only valid
- * values and the only danger is skipping too much.
+ * Regardless of being on LRU, compound pages such as THP
+ * (hugetlbfs is handled above) are not to be compacted unless
+ * we are attempting an allocation larger than the compound
+ * page size. We can potentially save a lot of iterations if we
+ * skip them at once. The check is racy, but we can consider
+ * only valid values and the only danger is skipping too much.
*/
if (PageCompound(page) && !cc->alloc_contig) {
const unsigned int order = compound_order(page);
- if (likely(order <= MAX_PAGE_ORDER)) {
- low_pfn += (1UL << order) - 1;
- nr_scanned += (1UL << order) - 1;
+ /* Skip based on page order and compaction target order. */
+ if (skip_isolation_on_order(order, cc->order)) {
+ if (order <= MAX_PAGE_ORDER) {
+ low_pfn += (1UL << order) - 1;
+ nr_scanned += (1UL << order) - 1;
+ }
+ goto isolate_fail;
}
- goto isolate_fail;
}
/*
@@ -1165,10 +1198,11 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
}
/*
- * folio become large since the non-locked check,
- * and it's on LRU.
+ * Check LRU folio order under the lock
*/
- if (unlikely(folio_test_large(folio) && !cc->alloc_contig)) {
+ if (unlikely(skip_isolation_on_order(folio_order(folio),
+ cc->order) &&
+ !cc->alloc_contig)) {
low_pfn += folio_nr_pages(folio) - 1;
nr_scanned += folio_nr_pages(folio) - 1;
folio_set_lru(folio);
@@ -1788,6 +1822,10 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data)
struct compact_control *cc = (struct compact_control *)data;
struct folio *dst;
+ /* this makes migrate_pages() split the source page and retry */
+ if (folio_test_large(src) > 0)
+ return NULL;
+
if (list_empty(&cc->freepages)) {
isolate_freepages(cc);
--
2.43.0
On Mon, Feb 12, 2024 at 9:35 AM Zi Yan <[email protected]> wrote:
>
> From: Zi Yan <[email protected]>
>
> 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.
>
> Signed-off-by: Zi Yan <[email protected]>
> Reviewed-by: Baolin Wang <[email protected]>
> Tested-by: Baolin Wang <[email protected]>
> Cc: Adam Manzanares <[email protected]>
> Cc: David Hildenbrand <[email protected]>
> Cc: Huang Ying <[email protected]>
> Cc: Johannes Weiner <[email protected]>
> Cc: Kemeng Shi <[email protected]>
> Cc: Kirill A. Shutemov <[email protected]>
> Cc: Luis Chamberlain <[email protected]>
> Cc: Matthew Wilcox (Oracle) <[email protected]>
> Cc: Mel Gorman <[email protected]>
> Cc: Ryan Roberts <[email protected]>
> Cc: Vishal Moola (Oracle) <[email protected]>
> Cc: Vlastimil Babka <[email protected]>
> Cc: Yin Fengwei <[email protected]>
> Cc: Yu Zhao <[email protected]>
> ---
> mm/compaction.c | 36 +++++++++++++++++++++++++++++++-----
> 1 file changed, 31 insertions(+), 5 deletions(-)
>
> diff --git a/mm/compaction.c b/mm/compaction.c
> index d0a05a621b67..25908e36b97c 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -1832,15 +1832,41 @@ 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;
> +
> +again:
> + for (start_order = order; start_order < NR_PAGE_ORDERS; start_order++)
> + if (!list_empty(&cc->freepages[start_order]))
> + break;
>
> - if (list_empty(&cc->freepages[order])) {
> - isolate_freepages(cc);
> - if (list_empty(&cc->freepages[order]))
> + /* no free pages in the list */
> + if (start_order == NR_PAGE_ORDERS) {
> + if (!has_isolated_pages) {
> + isolate_freepages(cc);
> + has_isolated_pages = true;
> + goto again;
> + } else
> return NULL;
Nit: remove the "else" above, or just:
if (has_isolated_pages)
return NULL;
isolate_freepages(cc);
has_isolated_pages = true;
goto again;
On 12 Feb 2024, at 13:27, Yu Zhao wrote:
> On Mon, Feb 12, 2024 at 9:35 AM Zi Yan <[email protected]> wrote:
>>
>> From: Zi Yan <[email protected]>
>>
>> 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.
>>
>> Signed-off-by: Zi Yan <[email protected]>
>> Reviewed-by: Baolin Wang <[email protected]>
>> Tested-by: Baolin Wang <[email protected]>
>> Cc: Adam Manzanares <[email protected]>
>> Cc: David Hildenbrand <[email protected]>
>> Cc: Huang Ying <[email protected]>
>> Cc: Johannes Weiner <[email protected]>
>> Cc: Kemeng Shi <[email protected]>
>> Cc: Kirill A. Shutemov <[email protected]>
>> Cc: Luis Chamberlain <[email protected]>
>> Cc: Matthew Wilcox (Oracle) <[email protected]>
>> Cc: Mel Gorman <[email protected]>
>> Cc: Ryan Roberts <[email protected]>
>> Cc: Vishal Moola (Oracle) <[email protected]>
>> Cc: Vlastimil Babka <[email protected]>
>> Cc: Yin Fengwei <[email protected]>
>> Cc: Yu Zhao <[email protected]>
>> ---
>> mm/compaction.c | 36 +++++++++++++++++++++++++++++++-----
>> 1 file changed, 31 insertions(+), 5 deletions(-)
>>
>> diff --git a/mm/compaction.c b/mm/compaction.c
>> index d0a05a621b67..25908e36b97c 100644
>> --- a/mm/compaction.c
>> +++ b/mm/compaction.c
>> @@ -1832,15 +1832,41 @@ 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;
>> +
>> +again:
>> + for (start_order = order; start_order < NR_PAGE_ORDERS; start_order++)
>> + if (!list_empty(&cc->freepages[start_order]))
>> + break;
>>
>> - if (list_empty(&cc->freepages[order])) {
>> - isolate_freepages(cc);
>> - if (list_empty(&cc->freepages[order]))
>> + /* no free pages in the list */
>> + if (start_order == NR_PAGE_ORDERS) {
>> + if (!has_isolated_pages) {
>> + isolate_freepages(cc);
>> + has_isolated_pages = true;
>> + goto again;
>> + } else
>> return NULL;
>
> Nit: remove the "else" above, or just:
>
> if (has_isolated_pages)
> return NULL;
> isolate_freepages(cc);
> has_isolated_pages = true;
> goto again;
Will do. Thanks.
--
Best Regards,
Yan, Zi
On Mon, Feb 12, 2024 at 9:35 AM Zi Yan <[email protected]> wrote:
>
> From: Zi Yan <[email protected]>
>
> Hi all,
>
> This patchset enables >0 order folio memory compaction, which is one of
> the prerequisitions for large folio support[1]. It is on top of
> mm-everything-2024-02-10-00-56.
>
> I am aware of that split free pages is necessary for folio
> migration in compaction, since if >0 order free pages are never split
> and no order-0 free page is scanned, compaction will end prematurely due
> to migration returns -ENOMEM. Free page split becomes a must instead of
> an optimization.
>
> lkp ncompare results (on a 8-CPU (Intel Xeon E5-2650 v4 @2.20GHz) 16G VM)
> for default LRU (-no-mglru) and CONFIG_LRU_GEN are shown at the bottom,
> copied from V3[4], since V4 is only a code refactoring of V3.
> In sum, most of vm-scalability applications do not see performance
> change, and the others see ~4% to ~26% performance boost under default LRU
> and ~2% to ~6% performance boost under CONFIG_LRU_GEN.
Suren has been testing 64KB THP on Android and seeing regressions
under memory pressure (a significant portion of client devices are
always under memory pressure). Hopefully this series will help.
I threw this series into some stress tests we have with both 64KB and
2MB THP enabled and didn't see any obvious problems.
Tested-by: Yu Zhao <[email protected]>
> Overview
> ===
>
> To support >0 order folio compaction, the patchset changes how free pages used
> for migration are kept during compaction. Free pages used to be split into
> order-0 pages that are post allocation processed (i.e., PageBuddy flag cleared,
> page order stored in page->private is zeroed, and page reference is set to 1).
> Now all free pages are kept in a MAX_ORDER+1 array of page lists based
> on their order without post allocation process. When migrate_pages() asks for
> a new page, one of the free pages, based on the requested page order, is
> then processed and given out.
And THP <2MB would need this feature (spell it out).
> vm-scalability results on CONFIG_LRU_GEN
> ===
>
> =========================================================================================
> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
> gcc-13/defconfig/debian/300s/qemu-vm/mmap-xread-seq-mt/vm-scalability
>
> commit:
> 6.8.0-rc1-mm-everything-2024-01-29-07-19+
> 6.8.0-rc1-split-folio-in-compaction+
> 6.8.0-rc1-folio-migration-in-compaction+
> 6.8.0-rc1-folio-migration-free-page-split+
>
> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
> ---------------- --------------------------- --------------------------- ---------------------------
> %stddev %change %stddev %change %stddev %change %stddev
> \ | \ | \ | \
> 15107616 +3.2% 15590339 +1.3% 15297619 +3.0% 15567998 vm-scalability.throughput
>
> =========================================================================================
> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
> gcc-13/defconfig/debian/300s/qemu-vm/mmap-pread-seq/vm-scalability
>
> commit:
> 6.8.0-rc1-mm-everything-2024-01-29-07-19+
> 6.8.0-rc1-split-folio-in-compaction+
> 6.8.0-rc1-folio-migration-in-compaction+
> 6.8.0-rc1-folio-migration-free-page-split+
>
> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
> ---------------- --------------------------- --------------------------- ---------------------------
> %stddev %change %stddev %change %stddev %change %stddev
> \ | \ | \ | \
> 12611785 +1.8% 12832919 +0.9% 12724223 +1.6% 12812682 vm-scalability.throughput
>
>
> =========================================================================================
> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
> gcc-13/defconfig/debian/300s/qemu-vm/lru-file-readtwice/vm-scalability
>
> commit:
> 6.8.0-rc1-mm-everything-2024-01-29-07-19+
> 6.8.0-rc1-split-folio-in-compaction+
> 6.8.0-rc1-folio-migration-in-compaction+
> 6.8.0-rc1-folio-migration-free-page-split+
>
> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
> ---------------- --------------------------- --------------------------- ---------------------------
> %stddev %change %stddev %change %stddev %change %stddev
> \ | \ | \ | \
> 9833393 +5.7% 10390190 +3.0% 10126606 +5.9% 10408804 vm-scalability.throughput
>
> =========================================================================================
> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
> gcc-13/defconfig/debian/300s/qemu-vm/lru-file-mmap-read/vm-scalability
>
> commit:
> 6.8.0-rc1-mm-everything-2024-01-29-07-19+
> 6.8.0-rc1-split-folio-in-compaction+
> 6.8.0-rc1-folio-migration-in-compaction+
> 6.8.0-rc1-folio-migration-free-page-split+
>
> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
> ---------------- --------------------------- --------------------------- ---------------------------
> %stddev %change %stddev %change %stddev %change %stddev
> \ | \ | \ | \
> 7034709 ± 3% +2.9% 7241429 +3.2% 7256680 ± 2% +3.9% 7308375 vm-scalability.throughput
>
>
>
> vm-scalability results on default LRU (with -no-mglru suffix)
> ===
>
> =========================================================================================
> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
> gcc-13/defconfig/debian/300s/qemu-vm/mmap-xread-seq-mt/vm-scalability
>
> commit:
> 6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
> 6.8.0-rc1-split-folio-in-compaction-no-mglru+
> 6.8.0-rc1-folio-migration-in-compaction-no-mglru+
> 6.8.0-rc1-folio-migration-free-page-split-no-mglru+
>
> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
> ---------------- --------------------------- --------------------------- ---------------------------
> %stddev %change %stddev %change %stddev %change %stddev
> \ | \ | \ | \
> 14401491 +3.7% 14940270 +2.4% 14748626 +4.0% 14975716 vm-scalability.throughput
>
> =========================================================================================
> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
> gcc-13/defconfig/debian/300s/qemu-vm/mmap-pread-seq/vm-scalability
>
> commit:
> 6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
> 6.8.0-rc1-split-folio-in-compaction-no-mglru+
> 6.8.0-rc1-folio-migration-in-compaction-no-mglru+
> 6.8.0-rc1-folio-migration-free-page-split-no-mglru+
>
> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
> ---------------- --------------------------- --------------------------- ---------------------------
> %stddev %change %stddev %change %stddev %change %stddev
> \ | \ | \ | \
> 11407497 +5.1% 11989632 -0.5% 11349272 +4.8% 11957423 vm-scalability.throughput
>
> =========================================================================================
> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
> gcc-13/defconfig/debian/300s/qemu-vm/mmap-pread-seq-mt/vm-scalability
>
> commit:
> 6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
> 6.8.0-rc1-split-folio-in-compaction-no-mglru+
> 6.8.0-rc1-folio-migration-in-compaction-no-mglru+
> 6.8.0-rc1-folio-migration-free-page-split-no-mglru+
>
> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
> ---------------- --------------------------- --------------------------- ---------------------------
> %stddev %change %stddev %change %stddev %change %stddev
> \ | \ | \ | \
> 11348474 +3.3% 11719453 -1.2% 11208759 +3.7% 11771926 vm-scalability.throughput
>
> =========================================================================================
> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
> gcc-13/defconfig/debian/300s/qemu-vm/lru-file-readtwice/vm-scalability
>
> commit:
> 6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
> 6.8.0-rc1-split-folio-in-compaction-no-mglru+
> 6.8.0-rc1-folio-migration-in-compaction-no-mglru+
> 6.8.0-rc1-folio-migration-free-page-split-no-mglru+
>
> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
> ---------------- --------------------------- --------------------------- ---------------------------
> %stddev %change %stddev %change %stddev %change %stddev
> \ | \ | \ | \
> 8065614 ± 3% +7.7% 8686626 ± 2% +5.0% 8467577 ± 4% +11.8% 9016077 ± 2% vm-scalability.throughput
>
> =========================================================================================
> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
> gcc-13/defconfig/debian/300s/qemu-vm/lru-file-mmap-read/vm-scalability
>
> commit:
> 6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
> 6.8.0-rc1-split-folio-in-compaction-no-mglru+
> 6.8.0-rc1-folio-migration-in-compaction-no-mglru+
> 6.8.0-rc1-folio-migration-free-page-split-no-mglru+
>
> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
> ---------------- --------------------------- --------------------------- ---------------------------
> %stddev %change %stddev %change %stddev %change %stddev
> \ | \ | \ | \
> 6438422 ± 2% +27.5% 8206734 ± 2% +10.6% 7118390 +26.2% 8127192 ± 4% vm-scalability.throughput
Thanks for the data! Based on the above:
Test case default MGLRU Change
=============================================================
mmap-xread-seq-mt/vm-scalability 14975716 15567998 +4%
mmap-pread-seq/vm-scalability 11957423 12812682 +7%
mmap-pread-seq-mt/vm-scalability 11771926 unavail N/A
lru-file-readtwice/vm-scalability 9016077 10408804 +15%
lru-file-mmap-read/vm-scalability 8127192 7308375 -10%
So it seems that MGLRU regressed for the last test. I'll find someone
on our team to take a look.
On 12 Feb 2024, at 13:44, Yu Zhao wrote:
> On Mon, Feb 12, 2024 at 9:35 AM Zi Yan <[email protected]> wrote:
>>
>> From: Zi Yan <[email protected]>
>>
>> Hi all,
>>
>> This patchset enables >0 order folio memory compaction, which is one of
>> the prerequisitions for large folio support[1]. It is on top of
>> mm-everything-2024-02-10-00-56.
>>
>> I am aware of that split free pages is necessary for folio
>> migration in compaction, since if >0 order free pages are never split
>> and no order-0 free page is scanned, compaction will end prematurely due
>> to migration returns -ENOMEM. Free page split becomes a must instead of
>> an optimization.
>>
>> lkp ncompare results (on a 8-CPU (Intel Xeon E5-2650 v4 @2.20GHz) 16G VM)
>> for default LRU (-no-mglru) and CONFIG_LRU_GEN are shown at the bottom,
>> copied from V3[4], since V4 is only a code refactoring of V3.
>> In sum, most of vm-scalability applications do not see performance
>> change, and the others see ~4% to ~26% performance boost under default LRU
>> and ~2% to ~6% performance boost under CONFIG_LRU_GEN.
>
> Suren has been testing 64KB THP on Android and seeing regressions
> under memory pressure (a significant portion of client devices are
> always under memory pressure). Hopefully this series will help.
>
> I threw this series into some stress tests we have with both 64KB and
> 2MB THP enabled and didn't see any obvious problems.
>
> Tested-by: Yu Zhao <[email protected]>
Thank you for the testing.
>
>> Overview
>> ===
>>
>> To support >0 order folio compaction, the patchset changes how free pages used
>> for migration are kept during compaction. Free pages used to be split into
>> order-0 pages that are post allocation processed (i.e., PageBuddy flag cleared,
>> page order stored in page->private is zeroed, and page reference is set to 1).
>> Now all free pages are kept in a MAX_ORDER+1 array of page lists based
>> on their order without post allocation process. When migrate_pages() asks for
>> a new page, one of the free pages, based on the requested page order, is
>> then processed and given out.
>
> And THP <2MB would need this feature (spell it out).
Will add this.
>
>
>
>> vm-scalability results on CONFIG_LRU_GEN
>> ===
>>
>> =========================================================================================
>> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
>> gcc-13/defconfig/debian/300s/qemu-vm/mmap-xread-seq-mt/vm-scalability
>>
>> commit:
>> 6.8.0-rc1-mm-everything-2024-01-29-07-19+
>> 6.8.0-rc1-split-folio-in-compaction+
>> 6.8.0-rc1-folio-migration-in-compaction+
>> 6.8.0-rc1-folio-migration-free-page-split+
>>
>> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
>> ---------------- --------------------------- --------------------------- ---------------------------
>> %stddev %change %stddev %change %stddev %change %stddev
>> \ | \ | \ | \
>> 15107616 +3.2% 15590339 +1.3% 15297619 +3.0% 15567998 vm-scalability.throughput
>>
>> =========================================================================================
>> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
>> gcc-13/defconfig/debian/300s/qemu-vm/mmap-pread-seq/vm-scalability
>>
>> commit:
>> 6.8.0-rc1-mm-everything-2024-01-29-07-19+
>> 6.8.0-rc1-split-folio-in-compaction+
>> 6.8.0-rc1-folio-migration-in-compaction+
>> 6.8.0-rc1-folio-migration-free-page-split+
>>
>> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
>> ---------------- --------------------------- --------------------------- ---------------------------
>> %stddev %change %stddev %change %stddev %change %stddev
>> \ | \ | \ | \
>> 12611785 +1.8% 12832919 +0.9% 12724223 +1.6% 12812682 vm-scalability.throughput
>>
>>
>> =========================================================================================
>> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
>> gcc-13/defconfig/debian/300s/qemu-vm/lru-file-readtwice/vm-scalability
>>
>> commit:
>> 6.8.0-rc1-mm-everything-2024-01-29-07-19+
>> 6.8.0-rc1-split-folio-in-compaction+
>> 6.8.0-rc1-folio-migration-in-compaction+
>> 6.8.0-rc1-folio-migration-free-page-split+
>>
>> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
>> ---------------- --------------------------- --------------------------- ---------------------------
>> %stddev %change %stddev %change %stddev %change %stddev
>> \ | \ | \ | \
>> 9833393 +5.7% 10390190 +3.0% 10126606 +5.9% 10408804 vm-scalability.throughput
>>
>> =========================================================================================
>> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
>> gcc-13/defconfig/debian/300s/qemu-vm/lru-file-mmap-read/vm-scalability
>>
>> commit:
>> 6.8.0-rc1-mm-everything-2024-01-29-07-19+
>> 6.8.0-rc1-split-folio-in-compaction+
>> 6.8.0-rc1-folio-migration-in-compaction+
>> 6.8.0-rc1-folio-migration-free-page-split+
>>
>> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
>> ---------------- --------------------------- --------------------------- ---------------------------
>> %stddev %change %stddev %change %stddev %change %stddev
>> \ | \ | \ | \
>> 7034709 ± 3% +2.9% 7241429 +3.2% 7256680 ± 2% +3.9% 7308375 vm-scalability.throughput
>>
>>
>>
>> vm-scalability results on default LRU (with -no-mglru suffix)
>> ===
>>
>> =========================================================================================
>> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
>> gcc-13/defconfig/debian/300s/qemu-vm/mmap-xread-seq-mt/vm-scalability
>>
>> commit:
>> 6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
>> 6.8.0-rc1-split-folio-in-compaction-no-mglru+
>> 6.8.0-rc1-folio-migration-in-compaction-no-mglru+
>> 6.8.0-rc1-folio-migration-free-page-split-no-mglru+
>>
>> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
>> ---------------- --------------------------- --------------------------- ---------------------------
>> %stddev %change %stddev %change %stddev %change %stddev
>> \ | \ | \ | \
>> 14401491 +3.7% 14940270 +2.4% 14748626 +4.0% 14975716 vm-scalability.throughput
>>
>> =========================================================================================
>> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
>> gcc-13/defconfig/debian/300s/qemu-vm/mmap-pread-seq/vm-scalability
>>
>> commit:
>> 6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
>> 6.8.0-rc1-split-folio-in-compaction-no-mglru+
>> 6.8.0-rc1-folio-migration-in-compaction-no-mglru+
>> 6.8.0-rc1-folio-migration-free-page-split-no-mglru+
>>
>> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
>> ---------------- --------------------------- --------------------------- ---------------------------
>> %stddev %change %stddev %change %stddev %change %stddev
>> \ | \ | \ | \
>> 11407497 +5.1% 11989632 -0.5% 11349272 +4.8% 11957423 vm-scalability.throughput
>>
>> =========================================================================================
>> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
>> gcc-13/defconfig/debian/300s/qemu-vm/mmap-pread-seq-mt/vm-scalability
>>
>> commit:
>> 6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
>> 6.8.0-rc1-split-folio-in-compaction-no-mglru+
>> 6.8.0-rc1-folio-migration-in-compaction-no-mglru+
>> 6.8.0-rc1-folio-migration-free-page-split-no-mglru+
>>
>> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
>> ---------------- --------------------------- --------------------------- ---------------------------
>> %stddev %change %stddev %change %stddev %change %stddev
>> \ | \ | \ | \
>> 11348474 +3.3% 11719453 -1.2% 11208759 +3.7% 11771926 vm-scalability.throughput
>>
>> =========================================================================================
>> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
>> gcc-13/defconfig/debian/300s/qemu-vm/lru-file-readtwice/vm-scalability
>>
>> commit:
>> 6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
>> 6.8.0-rc1-split-folio-in-compaction-no-mglru+
>> 6.8.0-rc1-folio-migration-in-compaction-no-mglru+
>> 6.8.0-rc1-folio-migration-free-page-split-no-mglru+
>>
>> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
>> ---------------- --------------------------- --------------------------- ---------------------------
>> %stddev %change %stddev %change %stddev %change %stddev
>> \ | \ | \ | \
>> 8065614 ± 3% +7.7% 8686626 ± 2% +5.0% 8467577 ± 4% +11.8% 9016077 ± 2% vm-scalability.throughput
>>
>> =========================================================================================
>> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
>> gcc-13/defconfig/debian/300s/qemu-vm/lru-file-mmap-read/vm-scalability
>>
>> commit:
>> 6.8.0-rc1-mm-everything-2024-01-29-07-19-no-mglru+
>> 6.8.0-rc1-split-folio-in-compaction-no-mglru+
>> 6.8.0-rc1-folio-migration-in-compaction-no-mglru+
>> 6.8.0-rc1-folio-migration-free-page-split-no-mglru+
>>
>> 6.8.0-rc1-mm-eve 6.8.0-rc1-split-folio-in-co 6.8.0-rc1-folio-migration-i 6.8.0-rc1-folio-migration-f
>> ---------------- --------------------------- --------------------------- ---------------------------
>> %stddev %change %stddev %change %stddev %change %stddev
>> \ | \ | \ | \
>> 6438422 ± 2% +27.5% 8206734 ± 2% +10.6% 7118390 +26.2% 8127192 ± 4% vm-scalability.throughput
>
> Thanks for the data! Based on the above:
>
> Test case default MGLRU Change
> =============================================================
> mmap-xread-seq-mt/vm-scalability 14975716 15567998 +4%
> mmap-pread-seq/vm-scalability 11957423 12812682 +7%
> mmap-pread-seq-mt/vm-scalability 11771926 unavail N/A
> lru-file-readtwice/vm-scalability 9016077 10408804 +15%
> lru-file-mmap-read/vm-scalability 8127192 7308375 -10%
>
> So it seems that MGLRU regressed for the last test. I'll find someone
> on our team to take a look.
Thanks.
--
Best Regards,
Yan, Zi