linux-kernel - Re: [PATCH v7 07/70] Maple Tree: Add new data structure

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Date:   Wed, 20 Apr 2022 13:47:53 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Yu Zhao <yuzhao@...gle.com>
Subject: Re: [PATCH v7 07/70] Maple Tree: Add new data structure

* Liam Howlett <liam.howlett@...cle.com> [220404 10:45]:
> From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
> 
> The maple tree is an RCU-safe range based B-tree designed to use modern
> processor cache efficiently.  There are a number of places in the kernel
> that a non-overlapping range-based tree would be beneficial, especially
> one with a simple interface.  The first user that is covered in this
> patch set is the vm_area_struct, where three data structures are
> replaced by the maple tree: the augmented rbtree, the vma cache, and the
> linked list of VMAs in the mm_struct.  The long term goal is to reduce
> or remove the mmap_sem contention.
> 
> The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf
> nodes.  With the increased branching factor, it is significantly shorter than
> the rbtree so it has fewer cache misses.  The removal of the linked list
> between subsequent entries also reduces the cache misses and the need to pull
> in the previous and next VMA during many tree alterations.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> Tested-by: David Howells <dhowells@...hat.com>
> ---
>  Documentation/core-api/index.rst              |    1 +
>  Documentation/core-api/maple_tree.rst         |  218 +
>  MAINTAINERS                                   |   12 +
>  include/linux/maple_tree.h                    |  682 ++
>  include/trace/events/maple_tree.h             |  123 +
>  init/main.c                                   |    2 +
>  lib/Kconfig.debug                             |   15 +
>  lib/Makefile                                  |    3 +-
>  lib/maple_tree.c                              | 6979 +++++++++++++++++
>  tools/testing/radix-tree/.gitignore           |    2 +
>  tools/testing/radix-tree/generated/autoconf.h |    1 +
>  tools/testing/radix-tree/linux/maple_tree.h   |    7 +
>  tools/testing/radix-tree/maple.c              |   59 +
>  .../radix-tree/trace/events/maple_tree.h      |    3 +
>  14 files changed, 8106 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/core-api/maple_tree.rst
>  create mode 100644 include/linux/maple_tree.h
>  create mode 100644 include/trace/events/maple_tree.h
>  create mode 100644 lib/maple_tree.c
>  create mode 100644 tools/testing/radix-tree/linux/maple_tree.h
>  create mode 100644 tools/testing/radix-tree/maple.c
>  create mode 100644 tools/testing/radix-tree/trace/events/maple_tree.h
> 

...

Andrew,

Please add this fix to the maple tree patch.


Thanks,
Liam

View attachment "0001-maple_tree-Fix-potential-insufficient-nodes-on-mas_s.patch" of type "text/x-diff" (1181 bytes)