Re: [PATCH v4 0/3] Enable >0 order folio memory compaction
From: Yu Zhao
Date: Mon Feb 12 2024 - 13:48:32 EST
On Mon, Feb 12, 2024 at 9:35 AM Zi Yan <zi.yan@xxxxxxxx> wrote:
>
> 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.
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 <yuzhao@xxxxxxxxxx>
> 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.