From: Suren Baghdasaryan <surenb@google.com>
To: akpm@linux-foundation.org
Cc: kent.overstreet@linux.dev, mhocko@suse.com, vbabka@suse.cz,
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Subject: [PATCH v4 36/36] memprofiling: Documentation
Date: Wed, 21 Feb 2024 11:40:49 -0800 [thread overview]
Message-ID: <20240221194052.927623-37-surenb@google.com> (raw)
In-Reply-To: <20240221194052.927623-1-surenb@google.com>
From: Kent Overstreet <kent.overstreet@linux.dev>
Provide documentation for memory allocation profiling.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
Documentation/mm/allocation-profiling.rst | 86 +++++++++++++++++++++++
1 file changed, 86 insertions(+)
create mode 100644 Documentation/mm/allocation-profiling.rst
diff --git a/Documentation/mm/allocation-profiling.rst b/Documentation/mm/allocation-profiling.rst
new file mode 100644
index 000000000000..2bcbd9e51fe4
--- /dev/null
+++ b/Documentation/mm/allocation-profiling.rst
@@ -0,0 +1,86 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===========================
+MEMORY ALLOCATION PROFILING
+===========================
+
+Low overhead (suitable for production) accounting of all memory allocations,
+tracked by file and line number.
+
+Usage:
+kconfig options:
+ - CONFIG_MEM_ALLOC_PROFILING
+ - CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
+ - CONFIG_MEM_ALLOC_PROFILING_DEBUG
+ adds warnings for allocations that weren't accounted because of a
+ missing annotation
+
+Boot parameter:
+ sysctl.vm.mem_profiling=1
+
+sysctl:
+ /proc/sys/vm/mem_profiling
+
+Runtime info:
+ /proc/allocinfo
+
+Example output:
+ root@moria-kvm:~# sort -g /proc/allocinfo|tail|numfmt --to=iec
+ 2.8M 22648 fs/kernfs/dir.c:615 func:__kernfs_new_node
+ 3.8M 953 mm/memory.c:4214 func:alloc_anon_folio
+ 4.0M 1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start
+ 4.1M 4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable
+ 6.0M 1532 mm/filemap.c:1919 func:__filemap_get_folio
+ 8.8M 2785 kernel/fork.c:307 func:alloc_thread_stack_node
+ 13M 234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs
+ 14M 3520 mm/mm_init.c:2530 func:alloc_large_system_hash
+ 15M 3656 mm/readahead.c:247 func:page_cache_ra_unbounded
+ 55M 4887 mm/slub.c:2259 func:alloc_slab_page
+ 122M 31168 mm/page_ext.c:270 func:alloc_page_ext
+===================
+Theory of operation
+===================
+
+Memory allocation profiling builds off of code tagging, which is a library for
+declaring static structs (that typcially describe a file and line number in
+some way, hence code tagging) and then finding and operating on them at runtime
+- i.e. iterating over them to print them in debugfs/procfs.
+
+To add accounting for an allocation call, we replace it with a macro
+invocation, alloc_hooks(), that
+ - declares a code tag
+ - stashes a pointer to it in task_struct
+ - calls the real allocation function
+ - and finally, restores the task_struct alloc tag pointer to its previous value.
+
+This allows for alloc_hooks() calls to be nested, with the most recent one
+taking effect. This is important for allocations internal to the mm/ code that
+do not properly belong to the outer allocation context and should be counted
+separately: for example, slab object extension vectors, or when the slab
+allocates pages from the page allocator.
+
+Thus, proper usage requires determining which function in an allocation call
+stack should be tagged. There are many helper functions that essentially wrap
+e.g. kmalloc() and do a little more work, then are called in multiple places;
+we'll generally want the accounting to happen in the callers of these helpers,
+not in the helpers themselves.
+
+To fix up a given helper, for example foo(), do the following:
+ - switch its allocation call to the _noprof() version, e.g. kmalloc_noprof()
+ - rename it to foo_noprof()
+ - define a macro version of foo() like so:
+ #define foo(...) alloc_hooks(foo_noprof(__VA_ARGS__))
+
+It's also possible to stash a pointer to an alloc tag in your own data structures.
+
+Do this when you're implementing a generic data structure that does allocations
+"on behalf of" some other code - for example, the rhashtable code. This way,
+instead of seeing a large line in /proc/allocinfo for rhashtable.c, we can
+break it out by rhashtable type.
+
+To do so:
+ - Hook your data structure's init function, like any other allocation function
+ - Within your init function, use the convenience macro alloc_tag_record() to
+ record alloc tag in your data structure.
+ - Then, use the following form for your allocations:
+ alloc_hooks_tag(ht->your_saved_tag, kmalloc_noprof(...))
--
2.44.0.rc0.258.g7320e95886-goog
next prev parent reply other threads:[~2024-02-21 19:42 UTC|newest]
Thread overview: 97+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-21 19:40 [PATCH v4 00/36] Memory allocation profiling Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 01/36] fix missing vmalloc.h includes Suren Baghdasaryan
2024-02-21 21:09 ` Pasha Tatashin
2024-02-21 19:40 ` [PATCH v4 02/36] asm-generic/io.h: Kill vmalloc.h dependency Suren Baghdasaryan
2024-02-21 21:11 ` Pasha Tatashin
2024-02-21 19:40 ` [PATCH v4 03/36] mm/slub: Mark slab_free_freelist_hook() __always_inline Suren Baghdasaryan
2024-02-21 21:15 ` Pasha Tatashin
2024-02-24 2:02 ` Suren Baghdasaryan
2024-02-26 14:31 ` Vlastimil Babka
[not found] ` <CA+CK2bBggtq6M96Pu49BmG_j01Sv6p_84Go++9APuvVPXHMwvQ@mail.gmail.com>
2024-02-26 16:09 ` Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 04/36] scripts/kallysms: Always include __start and __stop symbols Suren Baghdasaryan
2024-02-21 21:20 ` Pasha Tatashin
2024-02-21 19:40 ` [PATCH v4 05/36] fs: Convert alloc_inode_sb() to a macro Suren Baghdasaryan
2024-02-21 21:23 ` Pasha Tatashin
2024-02-26 15:44 ` Vlastimil Babka
2024-02-26 17:48 ` Suren Baghdasaryan
2024-02-26 20:50 ` Kent Overstreet
2024-02-21 19:40 ` [PATCH v4 06/36] mm: enumerate all gfp flags Suren Baghdasaryan
2024-02-21 21:25 ` Pasha Tatashin
2024-02-22 12:12 ` Michal Hocko
2024-02-22 12:24 ` Petr Tesařík
2024-02-23 19:26 ` Suren Baghdasaryan
2024-02-24 1:59 ` Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 07/36] mm: introduce slabobj_ext to support slab object extensions Suren Baghdasaryan
2024-02-21 21:30 ` Pasha Tatashin
2024-02-26 16:26 ` Vlastimil Babka
2024-02-26 17:22 ` Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 08/36] mm: introduce __GFP_NO_OBJ_EXT flag to selectively prevent slabobj_ext creation Suren Baghdasaryan
2024-02-22 0:08 ` Pasha Tatashin
2024-02-26 16:51 ` Vlastimil Babka
2024-02-21 19:40 ` [PATCH v4 09/36] mm/slab: introduce SLAB_NO_OBJ_EXT to avoid obj_ext creation Suren Baghdasaryan
2024-02-22 0:09 ` Pasha Tatashin
2024-02-26 16:52 ` Vlastimil Babka
2024-02-21 19:40 ` [PATCH v4 10/36] slab: objext: introduce objext_flags as extension to page_memcg_data_flags Suren Baghdasaryan
2024-02-22 0:12 ` Pasha Tatashin
2024-02-26 16:53 ` Vlastimil Babka
2024-02-21 19:40 ` [PATCH v4 11/36] lib: code tagging framework Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 12/36] lib: code tagging module support Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 13/36] lib: prevent module unloading if memory is not freed Suren Baghdasaryan
2024-02-26 16:58 ` Vlastimil Babka
2024-02-26 17:13 ` Suren Baghdasaryan
2024-03-12 18:23 ` Luis Chamberlain
2024-03-12 19:56 ` Suren Baghdasaryan
2024-03-12 20:07 ` Kent Overstreet
2024-02-21 19:40 ` [PATCH v4 14/36] lib: add allocation tagging support for memory allocation profiling Suren Baghdasaryan
2024-02-21 23:05 ` Kees Cook
2024-02-21 23:29 ` Kent Overstreet
2024-02-22 0:25 ` Kees Cook
2024-02-22 0:34 ` Kent Overstreet
2024-02-22 0:57 ` Kees Cook
2024-02-28 8:29 ` Vlastimil Babka
2024-02-28 18:05 ` Suren Baghdasaryan
2024-02-28 8:41 ` Vlastimil Babka
2024-02-28 18:07 ` Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 15/36] lib: introduce support for page allocation tagging Suren Baghdasaryan
2024-02-26 17:07 ` Vlastimil Babka
2024-02-26 17:11 ` Suren Baghdasaryan
2024-02-27 9:30 ` Vlastimil Babka
2024-02-27 9:45 ` Kent Overstreet
2024-02-27 16:55 ` Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 16/36] mm: percpu: increase PERCPU_MODULE_RESERVE to accommodate allocation tags Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 17/36] change alloc_pages name in dma_map_ops to avoid name conflicts Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 18/36] mm: enable page allocation tagging Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 19/36] mm: create new codetag references during page splitting Suren Baghdasaryan
2024-02-27 10:11 ` Vlastimil Babka
2024-02-27 16:38 ` Suren Baghdasaryan
2024-02-28 8:47 ` Vlastimil Babka
2024-02-28 17:50 ` Suren Baghdasaryan
2024-02-28 18:28 ` Vlastimil Babka
2024-02-28 18:38 ` Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 20/36] mm/page_ext: enable early_page_ext when CONFIG_MEM_ALLOC_PROFILING_DEBUG=y Suren Baghdasaryan
2024-02-27 10:18 ` Vlastimil Babka
2024-02-21 19:40 ` [PATCH v4 21/36] lib: add codetag reference into slabobj_ext Suren Baghdasaryan
2024-02-27 10:19 ` Vlastimil Babka
2024-02-21 19:40 ` [PATCH v4 22/36] mm/slab: add allocation accounting into slab allocation and free paths Suren Baghdasaryan
2024-02-27 13:07 ` Vlastimil Babka
2024-02-27 16:15 ` Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 23/36] mm/slab: enable slab allocation tagging for kmalloc and friends Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 24/36] rust: Add a rust helper for krealloc() Suren Baghdasaryan
2024-02-22 9:59 ` Alice Ryhl
2024-02-23 22:17 ` Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 25/36] mempool: Hook up to memory allocation profiling Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 26/36] mm: percpu: Introduce pcpuobj_ext Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 27/36] mm: percpu: Add codetag reference into pcpuobj_ext Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 28/36] mm: percpu: enable per-cpu allocation tagging Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 29/36] mm: vmalloc: Enable memory allocation profiling Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 30/36] rhashtable: Plumb through alloc tag Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 31/36] lib: add memory allocations report in show_mem() Suren Baghdasaryan
2024-02-27 13:19 ` Vlastimil Babka
2024-02-27 16:12 ` Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 32/36] codetag: debug: skip objext checking when it's for objext itself Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 33/36] codetag: debug: mark codetags for reserved pages as empty Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 34/36] codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mark failed slab_ext allocations Suren Baghdasaryan
2024-02-21 19:40 ` [PATCH v4 35/36] MAINTAINERS: Add entries for code tagging and memory allocation profiling Suren Baghdasaryan
2024-02-21 19:40 ` Suren Baghdasaryan [this message]
2024-02-27 13:36 ` [PATCH v4 00/36] Memory " Vlastimil Babka
2024-02-27 16:10 ` Suren Baghdasaryan
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