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Peng Zhang 4ddcdc519b FROMGIT: maple_tree: add mt_free_one() and mt_attr() helpers 
Patch series "Introduce __mt_dup() to improve the performance of fork()", v7.

This series introduces __mt_dup() to improve the performance of fork().
During the duplication process of mmap, all VMAs are traversed and
inserted one by one into the new maple tree, causing the maple tree to be
rebalanced multiple times.  Balancing the maple tree is a costly
operation.  To duplicate VMAs more efficiently, mtree_dup() and __mt_dup()
are introduced for the maple tree.  They can efficiently duplicate a maple
tree.

Here are some algorithmic details about {mtree,__mt}_dup().  We perform a
DFS pre-order traversal of all nodes in the source maple tree.  During
this process, we fully copy the nodes from the source tree to the new
tree.  This involves memory allocation, and when encountering a new node,
if it is a non-leaf node, all its child nodes are allocated at once.

This idea was originally from Liam R.  Howlett's Maple Tree Work email,
and I added some of my own ideas to implement it.  Some previous
discussions can be found in [1].  For a more detailed analysis of the
algorithm, please refer to the logs for patch [3/10] and patch [10/10].

There is a "spawn" in byte-unixbench[2], which can be used to test the
performance of fork().  I modified it slightly to make it work with
different number of VMAs.

Below are the test results.  The first row shows the number of VMAs.  The
second and third rows show the number of fork() calls per ten seconds,
corresponding to next-20231006 and the this patchset, respectively.  The
test results were obtained with CPU binding to avoid scheduler load
balancing that could cause unstable results.  There are still some
fluctuations in the test results, but at least they are better than the
original performance.

21     121   221    421    821    1621   3221   6421   12821  25621  51221
112100 76261 54227  34035  20195  11112  6017   3161   1606   802    393
114558 83067 65008  45824  28751  16072  8922   4747   2436   1233   599
2.19%  8.92% 19.88% 34.64% 42.37% 44.64% 48.28% 50.17% 51.68% 53.74% 52.42%

Thanks to Liam and Matthew for the review.

This patch (of 10):

Add two helpers:
1. mt_free_one(), used to free a maple node.
2. mt_attr(), used to obtain the attributes of maple tree.

Link: https://lkml.kernel.org/r/20231027033845.90608-1-zhangpeng.00@bytedance.com
Link: https://lkml.kernel.org/r/20231027033845.90608-2-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Mike Christie <michael.christie@oracle.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

(cherry picked from commit 4f2267b58a22d972be98edef8e6b3c7a67c9fb91
https://git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm mm-unstable)

Bug: 308042511
Change-Id: Ib9b13dee357ac4c85668901c20a3c370fbdd08da
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
2024-01-04 22:44:38 +00:00
android ANDROID: GKI: Enable symbols for v4l2 in async and fwnode 2024-01-04 22:25:09 +00:00
arch ANDROID: KVM: arm64: Fix hyp event alignment 2024-01-04 14:09:44 +00:00
block This is the 6.1.57 stable release 2023-11-02 07:05:54 +00:00
certs This is the 6.1.11 stable release 2023-02-09 13:29:55 +00:00
crypto Merge branch 'android14-6.1' into branch 'android14-6.1-lts' 2023-10-31 17:20:05 +00:00
Documentation BACKPORT: fscrypt: support crypto data unit size less than filesystem block size 2023-12-06 17:54:14 +00:00
drivers FROMGIT: PM / devfreq: Synchronize devfreq_monitor_[start/stop] 2024-01-03 23:14:47 +00:00
fs FROMGIT: f2fs: do not return EFSCORRUPTED, but try to run online repair 2024-01-04 10:39:11 +00:00
include UPSTREAM: maple_tree: introduce __mas_set_range() 2024-01-04 22:44:38 +00:00
init This is the 6.1.53 stable release 2023-09-18 09:57:37 +00:00
io_uring io_uring/fs: remove sqe->rw_flags checking from LINKAT 2023-10-06 14:57:02 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel ANDROID: Export functions to be used with dma_map_ops in modules 2024-01-03 20:45:29 +00:00
lib FROMGIT: maple_tree: add mt_free_one() and mt_attr() helpers 2024-01-04 22:44:38 +00:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm UPSTREAM: mm: handle write faults to RO pages under the VMA lock 2024-01-03 20:45:51 +00:00
net UPSTREAM: netfilter: nft_set_pipapo: skip inactive elements during set walk 2023-12-21 11:15:42 +00:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples Merge 6.1.55 into android14-6.1-lts 2023-10-26 18:58:32 +00:00
scripts ANDROID: Snapshot Mainline's version of checkpatch.pl 2023-12-15 09:36:46 +00:00
security This is the 6.1.57 stable release 2023-11-02 07:05:54 +00:00
sound UPSTREAM: ASoC: soc-compress: Fix deadlock in soc_compr_open_fe 2023-11-30 18:09:27 +00:00
tools ANDROID: fuse-bpf: Follow mounts in lookups 2023-12-20 23:12:56 +00:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes
.gitignore ANDROID: add Android KABI build files to root .gitignore file 2023-06-09 13:12:00 +00:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
BUILD.bazel ANDROID: ABI: Update sony symbol list and stg 2023-11-02 22:52:08 +00:00
build.config.aarch64 ANDROID: Move NDK_TRIPLE to build.config.constants. 2023-02-14 14:13:51 -08:00
build.config.allmodconfig ANDROID: Revert "ANDROID: allmodconfig: disable WERROR" 2023-08-21 17:29:29 +01:00
build.config.allmodconfig.aarch64 ANDROID: drop KERNEL_DIR setting in build.config.common 2020-08-31 15:20:37 +00:00
build.config.allmodconfig.arm ANDROID: drop KERNEL_DIR setting in build.config.common 2020-08-31 15:20:37 +00:00
build.config.allmodconfig.x86_64 ANDROID: drop KERNEL_DIR setting in build.config.common 2020-08-31 15:20:37 +00:00
build.config.amlogic ANDROID: Unnest MAKE_GOALS from build configs 2023-05-02 13:37:21 +00:00
build.config.arm ANDROID: kleaf: move NDK_TRIPLE for arm to build.config.constants. 2023-05-09 22:36:11 +00:00
build.config.common ANDROID: 6/16/2023 KMI update 2023-06-16 20:49:51 +00:00
build.config.constants ANDROID: clang: update to 17.0.2 2023-05-15 18:53:36 +00:00
build.config.crashdump ANDROID: Move microdroid and crashdump defconfigs to common 2023-09-27 15:30:26 +00:00
build.config.crashdump.aarch64 ANDROID: Move microdroid and crashdump defconfigs to common 2023-09-27 15:30:26 +00:00
build.config.crashdump.x86_64 ANDROID: Move microdroid and crashdump defconfigs to common 2023-09-27 15:30:26 +00:00
build.config.db845c ANDROID: db845c: Remove MAKE_GOALS from build.config 2023-05-15 07:01:39 +00:00
build.config.gki ANDROID: GKI: Source GKI_BUILD_CONFIG_FRAGMENT after setting all variables 2022-12-27 13:52:08 -08:00
build.config.gki-debug.aarch64 ANDROID: drop KERNEL_DIR setting in build.config.common 2020-08-31 15:20:37 +00:00
build.config.gki-debug.x86_64 ANDROID: drop KERNEL_DIR setting in build.config.common 2020-08-31 15:20:37 +00:00
build.config.gki.aarch64 ANDROID: Delete MODULES_LIST from build configs. 2023-06-21 11:18:02 +00:00
build.config.gki.aarch64.fips140 ANDROID: fips140: add kernel crypto module 2023-01-09 21:33:43 +00:00
build.config.gki.riscv64 ANDROID: Delete MODULES_LIST from build configs. 2023-06-21 11:18:02 +00:00
build.config.gki.x86_64 ANDROID: Delete MODULES_LIST from build configs. 2023-06-21 11:18:02 +00:00
build.config.gki_kasan ANDROID: build.config: re-disable LTO properly for KASAN 2022-03-24 12:41:35 -07:00
build.config.gki_kasan.aarch64 ANDROID: drop KERNEL_DIR setting in build.config.common 2020-08-31 15:20:37 +00:00
build.config.gki_kasan.x86_64 ANDROID: drop KERNEL_DIR setting in build.config.common 2020-08-31 15:20:37 +00:00
build.config.gki_kprobes ANDROID: build.configs: migrate away from CC_LD_ARG 2021-07-02 09:49:23 +00:00
build.config.gki_kprobes.aarch64 ANDROID: Adding kprobes build configs for Cuttlefish 2021-03-01 15:29:45 +00:00
build.config.gki_kprobes.x86_64 ANDROID: Adding kprobes build configs for Cuttlefish 2021-03-01 15:29:45 +00:00
build.config.khwasan ANDROID: Add a build config fragment for KHWASan. 2021-10-13 19:44:44 +00:00
build.config.microdroid ANDROID: Move microdroid and crashdump defconfigs to common 2023-09-27 15:30:26 +00:00
build.config.microdroid.aarch64 ANDROID: Move microdroid and crashdump defconfigs to common 2023-09-27 15:30:26 +00:00
build.config.microdroid.x86_64 ANDROID: Move microdroid and crashdump defconfigs to common 2023-09-27 15:30:26 +00:00
build.config.riscv64 ANDROID: GKI: Add 64-bit RISC-V config 2022-12-08 20:01:15 +00:00
build.config.rockchip ANDROID: GKI: Add rockchip fragment and build.config 2023-09-19 17:36:15 +00:00
build.config.rockpi4 ANDROID: db845c: Remove MAKE_GOALS from build.config 2023-05-15 07:01:39 +00:00
build.config.x86_64 ANDROID: Move NDK_TRIPLE to build.config.constants. 2023-02-14 14:13:51 -08:00
COPYING
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig ANDROID: kbuild: add Kconfig support for external modules 2021-12-13 18:33:18 +00:00
Kconfig.ext ANDROID: kbuild: add Kconfig support for external modules 2021-12-13 18:33:18 +00:00
MAINTAINERS Merge branch 'android14-6.1' into branch 'android14-6.1-lts' 2023-10-31 17:20:05 +00:00
Makefile This is the 6.1.57 stable release 2023-11-02 07:05:54 +00:00
modules.bzl ANDROID: kleaf: Remove ptp_kvm.ko from i386 modules 2023-08-31 17:47:21 +00:00
OWNERS ANDROID: Enable GKI Dr. No Enforcement 2023-06-15 09:54:33 +01:00
OWNERS_DrNo ANDROID: Updating OWNERS_DrNo 2022-08-22 16:34:52 +00:00
README
README.md ANDROID: README.md: fix checkpatch.pl path typo 2021-04-07 23:16:50 +00:00

README.md

How do I submit patches to Android Common Kernels

  1. BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases. These patches will be merged automatically in the corresponding common kernels. If the patch is already in upstream Linux, post a backport of the patch that conforms to the patch requirements below.

    • Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux, additions of EXPORT_SYMBOL_GPL() require an in-tree modular driver that uses the symbol -- so include the new driver or changes to an existing driver in the same patchset as the export.
    • When sending patches upstream, the commit message must contain a clear case for why the patch is needed and beneficial to the community. Enabling out-of-tree drivers or functionality is not not a persuasive case.

  2. LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these are fixing an Android-specific bug, these are very unlikely to be accepted unless they have been coordinated with kernel-team@android.com. If you want to proceed, post a patch that conforms to the patch requirements below.

Common Kernel patch requirements

  • All patches must conform to the Linux kernel coding standards and pass scripts/checkpatch.pl
  • Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures (see https://source.android.com/setup/build/building-kernels)
  • If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch: UPSTREAM:, BACKPORT:, FROMGIT:, FROMLIST:, or ANDROID:.
  • All patches must have a Change-Id: tag (see https://gerrit-review.googlesource.com/Documentation/user-changeid.html)
  • If an Android bug has been assigned, there must be a Bug: tag.
  • All patches must have a Signed-off-by: tag by the author and the submitter

Additional requirements are listed below based on patch type

Requirements for backports from mainline Linux: UPSTREAM:, BACKPORT:

  • If the patch is a cherry-pick from Linux mainline with no changes at all
    • tag the patch subject with UPSTREAM:.
    • add upstream commit information with a (cherry picked from commit ...) line
    • Example:
      • if the upstream commit message is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        UPSTREAM: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch requires any changes from the upstream version, tag the patch with BACKPORT: instead of UPSTREAM:.
    • use the same tags as UPSTREAM:
    • add comments about the changes under the (cherry picked from commit ...) line
    • Example:
        BACKPORT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        [joe: Resolved minor conflict in drivers/foo/bar.c ]
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for other backports: FROMGIT:, FROMLIST:,

  • If the patch has been merged into an upstream maintainer tree, but has not yet been merged into Linux mainline
    • tag the patch subject with FROMGIT:
    • add info on where the patch came from as (cherry picked from commit <sha1> <repo> <branch>). This must be a stable maintainer branch (not rebased, so don't use linux-next for example).
    • if changes were required, use BACKPORT: FROMGIT:
    • Example:
      • if the commit message in the maintainer tree is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        FROMGIT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        (cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace
         https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch has been submitted to LKML, but not accepted into any maintainer tree
    • tag the patch subject with FROMLIST:
    • add a Link: tag with a link to the submittal on lore.kernel.org
    • add a Bug: tag with the Android bug (required for patches not accepted into a maintainer tree)
    • if changes were required, use BACKPORT: FROMLIST:
    • Example:
        FROMLIST: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for Android-specific patches: ANDROID:

  • If the patch is fixing a bug to Android-specific code
    • tag the patch subject with ANDROID:
    • add a Fixes: tag that cites the patch with the bug
    • Example:
        ANDROID: fix android-specific bug in foobar.c

        This is the detailed description of the important fix

        Fixes: 1234abcd2468 ("foobar: add cool feature")
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch is a new feature
    • tag the patch subject with ANDROID:
    • add a Bug: tag with the Android bug (required for android-specific features)