From: Zi Yan <ziy@xxxxxxxxxx> 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/f8d47176-03a8-99bf-a813-b5942830fd73@xxxxxxx/ [2] https://lore.kernel.org/linux-mm/20231113170157.280181-1-zi.yan@xxxxxxxx/ [3] https://lore.kernel.org/linux-mm/20240123034636.1095672-1-zi.yan@xxxxxxxx/ [4] https://lore.kernel.org/linux-mm/20240202161554.565023-1-zi.yan@xxxxxxxx/ 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
