[PATCH v1 0/4] Enable >0 order folio memory compaction

Zi Yan
2023-11-13T17:02:21Z

From: Zi Yan <ziy@nvidia.com>

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-2023-10-21-02-40 (also applies to mm-everything-2023-11-10-20-42
without conflicts).

Per patch vm-scalability results on a 8-CPU (Intel Xeon E5-2650 v4 @ 2.20GHz)
16G VM are at the bottom and based on mm-everything-2023-10-21-02-40.
Each has 5 runs. Highlights:

1. mmap-pread-seq-mt: -18.3% if split folios during compaction and -7.7%
if migrating folios during compaction.

2. lru-file-readtwice: +41.5% if split folios during compaction and
+30.4% if migrating folios during compaction.

3. lru-file-mmap-read: +35.1% if split folios during compaction and
+32.3% if migrating folios during compaction.

I will run experiments on bare metal and report results later.

Changelog
===

From RFC:
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.

Optimizations
===

1. Free page split is added to increase migration success rate in case
a source page does not have a matched free page in the free page lists.
Free page merge is possible but not implemented, since existing
PFN-based buddy page merge algorithm requires the identification of
buddy pages, but free pages kept for memory compaction cannot have
PageBuddy set to avoid confusing other PFN scanners.

2. Sort source pages in ascending order before migration is added to
reduce free page split. Otherwise, high order free pages might be
prematurely split, causing undesired high order folio migration failures.

TODOs
===

1. Refactor free page post allocation and free page preparation code so
that compaction_alloc() and compaction_free() can call functions instead
of hard coding.

2. Make isolate_migratepages_block() produce a sorted list for
compaction to avoid sort_folio_by_order() in Patch 4.

Feel free to give comments and ask questions.

Thanks.

vm-scalability results
===

=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/mmap-xread-seq-mt/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
12896955 +2.7% 13249322 -4.0% 12385175 ± 5% +1.1% 13033951 -0.4% 12845698 vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/mmap-pread-seq/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
14626665 -5.5% 13825048 -1.7% 14384837 -1.9% 14345958 -2.0% 14338834 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:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
14314960 -18.3% 11691969 ± 2% -7.7% 13217795 -8.8% 13057395 -10.8% 12764204 vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/lru-file-readtwice/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
6498203 ± 6% +41.5% 9193356 +30.4% 8472024 +30.0% 8449054 ± 3% +32.3% 8596781 ± 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:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
5440732 ± 10% +35.1% 7352631 ± 9% +32.3% 7200622 ± 5% +27.0% 6909673 ± 4% +25.9% 6849852 ± 5% vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/qemu-vm/lru-file-mmap-read-rand/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
1627989 +0.3% 1632141 +1.8% 1656877 +0.1% 1629816 -0.2% 1625213 vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/8T/qemu-vm/anon-wx-seq-mt/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
6738043 +1.4% 6835096 +1.4% 6834329 +1.0% 6805401 +1.2% 6820637 vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/8T/qemu-vm/anon-w-seq-mt/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
7644894 +0.2% 7661425 +0.4% 7676929 +1.0% 7719218 +0.3% 7664658 vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/512G/qemu-vm/anon-wx-rand-mt/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
521941 +3.3% 539254 +3.3% 539213 +1.0% 527048 +3.4% 539588 vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/512G/qemu-vm/anon-w-rand/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
481028 +4.3% 501876 +2.4% 492713 +0.4% 482829 ± 2% +3.5% 497649 ± 2% vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/512G/qemu-vm/anon-w-rand-mt/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
477063 +4.0% 496373 +4.0% 496283 +1.4% 483966 +3.2% 492216 ± 2% vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/512G/qemu-vm/anon-cow-rand/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
458073 +3.3% 473056 +2.6% 469835 +0.3% 459266 +3.0% 471735 vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/512G/qemu-vm/anon-cow-rand-mt/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
468158 +0.8% 472115 +1.4% 474547 +1.1% 473307 +2.1% 478173 vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/2T/qemu-vm/shm-xread-seq/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
3489946 +1.4% 3540036 +0.4% 3505413 +1.7% 3549852 +1.4% 3539309 vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/2T/qemu-vm/shm-xread-seq-mt/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
2621783 +1.0% 2647480 +0.6% 2636399 +0.7% 2641150 +0.1% 2624301 vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/2T/qemu-vm/shm-pread-seq/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
3504293 +1.5% 3557664 -0.4% 3489639 +0.4% 3516842 +0.8% 3533944 vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/256G/qemu-vm/msync/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
919378 ± 6% +3.8% 954028 ± 10% +7.2% 985920 ± 6% +7.4% 987077 ± 5% +14.2% 1049473 ± 2% vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/256G/qemu-vm/msync-mt/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
2398063 +2.0% 2446844 -1.5% 2361096 ± 2% -3.1% 2324346 ± 4% -1.0% 2375055 ± 4% vm-scalability.throughput

=========================================================================================
compiler/kconfig/rootfs/runtime/size/tbox_group/test/testcase:
gcc-13/defconfig/debian/300s/128G/qemu-vm/truncate/vm-scalability

commit:
6.6.0-rc4-mm-everything-2023-10-21-02-40+
6.6.0-rc4-split-folio-in-compaction+
6.6.0-rc4-folio-migration-in-compaction+
6.6.0-rc4-folio-migration-free-page-split+
6.6.0-rc4-folio-migration-free-page-split-sort-src+

6.6.0-rc4-mm-eve 6.6.0-rc4-split-folio-in-co 6.6.0-rc4-folio-migration-i 6.6.0-rc4-folio-migration-f 6.6.0-rc4-folio-migration-f
---------------- --------------------------- --------------------------- --------------------------- ---------------------------
%stddev %change %stddev %change %stddev %change %stddev %change %stddev
\ | \ | \ | \ | \
2.084e+08 ± 2% +1.5% 2.114e+08 ± 3% +6.5% 2.22e+08 ± 3% -2.3% 2.035e+08 ± 2% -2.1% 2.04e+08 ± 5% vm-scalability.throughput

[1] https://lore.kernel.org/linux-mm/f8d47176-03a8-99bf-a813-b5942830fd73@arm.com/

Zi Yan (4):
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: optimize >0 order folio compaction by sorting source
pages.

mm/compaction.c | 280 ++++++++++++++++++++++++++++++++++++------------
mm/internal.h | 7 +-
2 files changed, 217 insertions(+), 70 deletions(-)

--
2.42.0