From: Hongru Zhang <zhanghongru06@gmail.com>
To: akpm@linux-foundation.org, vbabka@suse.cz, david@kernel.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
surenb@google.com, mhocko@suse.com, jackmanb@google.com,
hannes@cmpxchg.org, ziy@nvidia.com, lorenzo.stoakes@oracle.com,
Liam.Howlett@oracle.com, rppt@kernel.org,
axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com,
Hongru Zhang <zhanghongru@xiaomi.com>
Subject: [PATCH 0/3] mm: add per-migratetype counts to buddy allocator and optimize pagetypeinfo access
Date: Fri, 28 Nov 2025 11:10:11 +0800 [thread overview]
Message-ID: <cover.1764297987.git.zhanghongru@xiaomi.com> (raw)
On mobile devices, some user-space memory management components check
memory pressure and fragmentation status periodically or via PSI, and
take actions such as killing processes or performing memory compaction
based on this information.
Under high load scenarios, reading /proc/pagetypeinfo causes memory
management components or memory allocation/free paths to be blocked
for extended periods waiting for the zone lock, leading to the following
issues:
1. Long interrupt-disabled spinlocks - occasionally exceeding 10ms on Qcom
8750 platforms, reducing system real-time performance
2. Memory management components being blocked for extended periods,
preventing rapid acquisition of memory fragmentation information for
critical memory management decisions and actions
3. Increased latency in memory allocation and free paths due to prolonged
zone lock contention
Changes:
1. Add per-migratetype counts to the buddy allocator to track free page
block counts for each migratetype and order
2. Optimize /proc/pagetypeinfo access by utilizing these per-migratetype
counts instead of iterating through free lists under zone lock
Performance testing shows following improvements:
1. /proc/pagetypeinfo access latency reduced
+-----------------------+----------+------------+
| | no-patch | with-patch |
+-----------------------+----------+------------+
| Just after boot | 700.9 us | 268.6 us |
+-----------------------+----------+------------+
| After building kernel | 28.7 ms | 269.8 us |
+-----------------------+----------+------------+
2. When /proc/pagetypeinfo is accessed concurrently, memory allocation and
free performance degradation is reduced compared to the previous
implementation
Test setup:
- Using config-pagealloc-micro
- Monitor set to proc-pagetypeinfo, update frequency set to 10ms
- PAGEALLOC_ORDER_MIN=4, PAGEALLOC_ORDER_MAX=4
Without patch test results:
vanilla vanilla
no-monitor monitor
Min alloc-odr4-1 8539.00 ( 0.00%) 8762.00 ( -2.61%)
Min alloc-odr4-2 6501.00 ( 0.00%) 6683.00 ( -2.80%)
Min alloc-odr4-4 5537.00 ( 0.00%) 5873.00 ( -6.07%)
Min alloc-odr4-8 5030.00 ( 0.00%) 5361.00 ( -6.58%)
Min alloc-odr4-16 4782.00 ( 0.00%) 5162.00 ( -7.95%)
Min alloc-odr4-32 5838.00 ( 0.00%) 6499.00 ( -11.32%)
Min alloc-odr4-64 6565.00 ( 0.00%) 7413.00 ( -12.92%)
Min alloc-odr4-128 6896.00 ( 0.00%) 7898.00 ( -14.53%)
Min alloc-odr4-256 7303.00 ( 0.00%) 8163.00 ( -11.78%)
Min alloc-odr4-512 10179.00 ( 0.00%) 11985.00 ( -17.74%)
Min alloc-odr4-1024 11000.00 ( 0.00%) 12165.00 ( -10.59%)
Min free-odr4-1 820.00 ( 0.00%) 1230.00 ( -50.00%)
Min free-odr4-2 511.00 ( 0.00%) 952.00 ( -86.30%)
Min free-odr4-4 347.00 ( 0.00%) 434.00 ( -25.07%)
Min free-odr4-8 286.00 ( 0.00%) 399.00 ( -39.51%)
Min free-odr4-16 250.00 ( 0.00%) 405.00 ( -62.00%)
Min free-odr4-32 294.00 ( 0.00%) 405.00 ( -37.76%)
Min free-odr4-64 333.00 ( 0.00%) 363.00 ( -9.01%)
Min free-odr4-128 340.00 ( 0.00%) 412.00 ( -21.18%)
Min free-odr4-256 339.00 ( 0.00%) 329.00 ( 2.95%)
Min free-odr4-512 361.00 ( 0.00%) 409.00 ( -13.30%)
Min free-odr4-1024 300.00 ( 0.00%) 361.00 ( -20.33%)
Stddev alloc-odr4-1 7.29 ( 0.00%) 90.78 (-1146.00%)
Stddev alloc-odr4-2 3.87 ( 0.00%) 51.30 (-1225.75%)
Stddev alloc-odr4-4 3.20 ( 0.00%) 50.90 (-1491.24%)
Stddev alloc-odr4-8 4.67 ( 0.00%) 52.23 (-1019.35%)
Stddev alloc-odr4-16 5.72 ( 0.00%) 27.53 (-381.04%)
Stddev alloc-odr4-32 6.25 ( 0.00%) 641.23 (-10154.46%)
Stddev alloc-odr4-64 2.06 ( 0.00%) 386.99 (-18714.22%)
Stddev alloc-odr4-128 14.36 ( 0.00%) 52.39 (-264.77%)
Stddev alloc-odr4-256 32.42 ( 0.00%) 326.19 (-906.05%)
Stddev alloc-odr4-512 65.58 ( 0.00%) 184.49 (-181.31%)
Stddev alloc-odr4-1024 8.88 ( 0.00%) 153.01 (-1622.67%)
Stddev free-odr4-1 2.29 ( 0.00%) 152.27 (-6549.85%)
Stddev free-odr4-2 10.99 ( 0.00%) 73.10 (-564.89%)
Stddev free-odr4-4 1.99 ( 0.00%) 28.40 (-1324.45%)
Stddev free-odr4-8 2.51 ( 0.00%) 52.93 (-2007.64%)
Stddev free-odr4-16 2.85 ( 0.00%) 26.04 (-814.88%)
Stddev free-odr4-32 4.04 ( 0.00%) 27.05 (-569.79%)
Stddev free-odr4-64 2.10 ( 0.00%) 48.07 (-2185.66%)
Stddev free-odr4-128 2.63 ( 0.00%) 26.23 (-897.86%)
Stddev free-odr4-256 6.29 ( 0.00%) 37.04 (-488.71%)
Stddev free-odr4-512 2.56 ( 0.00%) 10.65 (-315.28%)
Stddev free-odr4-1024 0.95 ( 0.00%) 6.46 (-582.22%)
Max alloc-odr4-1 8564.00 ( 0.00%) 9099.00 ( -6.25%)
Max alloc-odr4-2 6511.00 ( 0.00%) 6844.00 ( -5.11%)
Max alloc-odr4-4 5549.00 ( 0.00%) 6038.00 ( -8.81%)
Max alloc-odr4-8 5045.00 ( 0.00%) 5551.00 ( -10.03%)
Max alloc-odr4-16 4800.00 ( 0.00%) 5257.00 ( -9.52%)
Max alloc-odr4-32 5861.00 ( 0.00%) 8115.00 ( -38.46%)
Max alloc-odr4-64 6571.00 ( 0.00%) 8292.00 ( -26.19%)
Max alloc-odr4-128 6930.00 ( 0.00%) 8081.00 ( -16.61%)
Max alloc-odr4-256 7372.00 ( 0.00%) 9150.00 ( -24.12%)
Max alloc-odr4-512 10333.00 ( 0.00%) 12636.00 ( -22.29%)
Max alloc-odr4-1024 11035.00 ( 0.00%) 12590.00 ( -14.09%)
Max free-odr4-1 828.00 ( 0.00%) 1724.00 (-108.21%)
Max free-odr4-2 543.00 ( 0.00%) 1192.00 (-119.52%)
Max free-odr4-4 354.00 ( 0.00%) 519.00 ( -46.61%)
Max free-odr4-8 293.00 ( 0.00%) 617.00 (-110.58%)
Max free-odr4-16 260.00 ( 0.00%) 483.00 ( -85.77%)
Max free-odr4-32 308.00 ( 0.00%) 488.00 ( -58.44%)
Max free-odr4-64 341.00 ( 0.00%) 505.00 ( -48.09%)
Max free-odr4-128 346.00 ( 0.00%) 497.00 ( -43.64%)
Max free-odr4-256 353.00 ( 0.00%) 463.00 ( -31.16%)
Max free-odr4-512 367.00 ( 0.00%) 442.00 ( -20.44%)
Max free-odr4-1024 303.00 ( 0.00%) 381.00 ( -25.74%)
With patch test results:
patched patched
no-monitor monitor
Min alloc-odr4-1 8488.00 ( 0.00%) 8514.00 ( -0.31%)
Min alloc-odr4-2 6551.00 ( 0.00%) 6527.00 ( 0.37%)
Min alloc-odr4-4 5536.00 ( 0.00%) 5591.00 ( -0.99%)
Min alloc-odr4-8 5008.00 ( 0.00%) 5098.00 ( -1.80%)
Min alloc-odr4-16 4760.00 ( 0.00%) 4857.00 ( -2.04%)
Min alloc-odr4-32 5827.00 ( 0.00%) 5919.00 ( -1.58%)
Min alloc-odr4-64 6561.00 ( 0.00%) 6680.00 ( -1.81%)
Min alloc-odr4-128 6898.00 ( 0.00%) 7014.00 ( -1.68%)
Min alloc-odr4-256 7311.00 ( 0.00%) 7464.00 ( -2.09%)
Min alloc-odr4-512 10181.00 ( 0.00%) 10286.00 ( -1.03%)
Min alloc-odr4-1024 11205.00 ( 0.00%) 11725.00 ( -4.64%)
Min free-odr4-1 789.00 ( 0.00%) 867.00 ( -9.89%)
Min free-odr4-2 490.00 ( 0.00%) 526.00 ( -7.35%)
Min free-odr4-4 350.00 ( 0.00%) 360.00 ( -2.86%)
Min free-odr4-8 272.00 ( 0.00%) 287.00 ( -5.51%)
Min free-odr4-16 247.00 ( 0.00%) 254.00 ( -2.83%)
Min free-odr4-32 298.00 ( 0.00%) 304.00 ( -2.01%)
Min free-odr4-64 334.00 ( 0.00%) 325.00 ( 2.69%)
Min free-odr4-128 334.00 ( 0.00%) 329.00 ( 1.50%)
Min free-odr4-256 336.00 ( 0.00%) 336.00 ( 0.00%)
Min free-odr4-512 360.00 ( 0.00%) 342.00 ( 5.00%)
Min free-odr4-1024 327.00 ( 0.00%) 355.00 ( -8.56%)
Stddev alloc-odr4-1 5.19 ( 0.00%) 45.38 (-775.09%)
Stddev alloc-odr4-2 6.99 ( 0.00%) 37.63 (-437.98%)
Stddev alloc-odr4-4 3.91 ( 0.00%) 17.85 (-356.28%)
Stddev alloc-odr4-8 5.15 ( 0.00%) 9.34 ( -81.47%)
Stddev alloc-odr4-16 3.83 ( 0.00%) 5.34 ( -39.34%)
Stddev alloc-odr4-32 1.96 ( 0.00%) 10.28 (-425.09%)
Stddev alloc-odr4-64 1.32 ( 0.00%) 333.30 (-25141.39%)
Stddev alloc-odr4-128 2.06 ( 0.00%) 7.37 (-258.28%)
Stddev alloc-odr4-256 15.56 ( 0.00%) 113.48 (-629.25%)
Stddev alloc-odr4-512 61.25 ( 0.00%) 165.09 (-169.53%)
Stddev alloc-odr4-1024 18.89 ( 0.00%) 2.93 ( 84.51%)
Stddev free-odr4-1 4.45 ( 0.00%) 40.12 (-800.98%)
Stddev free-odr4-2 1.50 ( 0.00%) 29.30 (-1850.31%)
Stddev free-odr4-4 1.27 ( 0.00%) 19.49 (-1439.40%)
Stddev free-odr4-8 0.97 ( 0.00%) 8.93 (-823.07%)
Stddev free-odr4-16 8.38 ( 0.00%) 4.51 ( 46.21%)
Stddev free-odr4-32 3.18 ( 0.00%) 6.59 (-107.42%)
Stddev free-odr4-64 2.40 ( 0.00%) 3.09 ( -28.50%)
Stddev free-odr4-128 1.55 ( 0.00%) 2.53 ( -62.92%)
Stddev free-odr4-256 0.41 ( 0.00%) 2.80 (-585.57%)
Stddev free-odr4-512 1.60 ( 0.00%) 4.84 (-202.08%)
Stddev free-odr4-1024 0.66 ( 0.00%) 1.19 ( -80.68%)
Max alloc-odr4-1 8505.00 ( 0.00%) 8676.00 ( -2.01%)
Max alloc-odr4-2 6572.00 ( 0.00%) 6651.00 ( -1.20%)
Max alloc-odr4-4 5552.00 ( 0.00%) 5646.00 ( -1.69%)
Max alloc-odr4-8 5024.00 ( 0.00%) 5131.00 ( -2.13%)
Max alloc-odr4-16 4774.00 ( 0.00%) 4875.00 ( -2.12%)
Max alloc-odr4-32 5834.00 ( 0.00%) 5950.00 ( -1.99%)
Max alloc-odr4-64 6565.00 ( 0.00%) 7434.00 ( -13.24%)
Max alloc-odr4-128 6907.00 ( 0.00%) 7034.00 ( -1.84%)
Max alloc-odr4-256 7347.00 ( 0.00%) 7843.00 ( -6.75%)
Max alloc-odr4-512 10315.00 ( 0.00%) 10866.00 ( -5.34%)
Max alloc-odr4-1024 11278.00 ( 0.00%) 11733.00 ( -4.03%)
Max free-odr4-1 803.00 ( 0.00%) 1009.00 ( -25.65%)
Max free-odr4-2 495.00 ( 0.00%) 607.00 ( -22.63%)
Max free-odr4-4 354.00 ( 0.00%) 417.00 ( -17.80%)
Max free-odr4-8 275.00 ( 0.00%) 313.00 ( -13.82%)
Max free-odr4-16 273.00 ( 0.00%) 272.00 ( 0.37%)
Max free-odr4-32 309.00 ( 0.00%) 324.00 ( -4.85%)
Max free-odr4-64 340.00 ( 0.00%) 335.00 ( 1.47%)
Max free-odr4-128 340.00 ( 0.00%) 338.00 ( 0.59%)
Max free-odr4-256 338.00 ( 0.00%) 346.00 ( -2.37%)
Max free-odr4-512 364.00 ( 0.00%) 359.00 ( 1.37%)
Max free-odr4-1024 329.00 ( 0.00%) 359.00 ( -9.12%)
The main overhead is a slight increase in latency on the memory allocation
and free paths due to additional per-migratetype counting, with
theoretically minimal impact on overall performance.
This patch series is based on v6.18-rc7
Hongru Zhang (3):
mm/page_alloc: add per-migratetype counts to buddy allocator
mm/vmstat: get fragmentation statistics from per-migragetype count
mm: optimize free_area_empty() check using per-migratetype counts
include/linux/mmzone.h | 1 +
mm/internal.h | 2 +-
mm/mm_init.c | 1 +
mm/page_alloc.c | 9 ++++++++-
mm/vmstat.c | 30 +++++++-----------------------
5 files changed, 18 insertions(+), 25 deletions(-)
--
2.43.0
next reply other threads:[~2025-11-28 3:10 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-28 3:10 Hongru Zhang [this message]
2025-11-28 3:11 ` [PATCH 1/3] mm/page_alloc: add per-migratetype counts to buddy allocator Hongru Zhang
2025-11-29 0:34 ` Barry Song
2025-11-28 3:12 ` [PATCH 2/3] mm/vmstat: get fragmentation statistics from per-migragetype count Hongru Zhang
2025-11-28 12:03 ` zhongjinji
2025-11-29 0:00 ` Barry Song
2025-11-29 7:55 ` Barry Song
2025-12-01 12:29 ` Hongru Zhang
2025-12-01 18:54 ` Barry Song
2025-11-28 3:12 ` [PATCH 3/3] mm: optimize free_area_empty() check using per-migratetype counts Hongru Zhang
2025-11-29 0:04 ` Barry Song
2025-11-29 9:24 ` Barry Song
2025-11-28 7:49 ` [PATCH 0/3] mm: add per-migratetype counts to buddy allocator and optimize pagetypeinfo access Lorenzo Stoakes
2025-11-28 8:34 ` Hongru Zhang
2025-11-28 8:40 ` Lorenzo Stoakes
2025-11-28 9:24 ` Vlastimil Babka
2025-11-28 13:08 ` Johannes Weiner
2025-12-01 2:36 ` Hongru Zhang
2025-12-01 17:01 ` Zi Yan
2025-12-02 2:42 ` Hongru Zhang
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