€•’D      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ+/translations/zh_CN/mm/allocation-profiling”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ+/translations/zh_TW/mm/allocation-profiling”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ+/translations/it_IT/mm/allocation-profiling”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ+/translations/ja_JP/mm/allocation-profiling”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ+/translations/ko_KR/mm/allocation-profiling”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ+/translations/sp_SP/mm/allocation-profiling”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒcomment”“”)”}”(hŒ SPDX-License-Identifier: GPL-2.0”h]”hŒ SPDX-License-Identifier: GPL-2.0”…””}”hh£sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1h¡hhhžhhŸŒE/var/lib/git/docbuild/linux/Documentation/mm/allocation-profiling.rst”h KubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒMEMORY ALLOCATION PROFILING”h]”hŒMEMORY ALLOCATION PROFILING”…””}”(hh»hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hh¶hžhhŸh³h KubhŒ	paragraph”“”)”}”(hŒmLow overhead (suitable for production) accounting of all memory allocations,
tracked by file and line number.”h]”hŒmLow overhead (suitable for production) accounting of all memory allocations,
tracked by file and line number.”…””}”(hhËhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Khh¶hžhubhÊ)”}”(hŒ4Usage:
kconfig options:
- CONFIG_MEM_ALLOC_PROFILING”h]”hŒ4Usage:
kconfig options:
- CONFIG_MEM_ALLOC_PROFILING”…””}”(hhÙhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K
hh¶hžhubhŒbullet_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hŒ.CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
”h]”hÊ)”}”(hŒ-CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT”h]”hŒ-CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT”…””}”(hhòhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Khhîubah}”(h]”h ]”h"]”h$]”h&]”uh1hìhhéhžhhŸh³h Nubhí)”}”(hŒvCONFIG_MEM_ALLOC_PROFILING_DEBUG
adds warnings for allocations that weren't accounted because of a
missing annotation
”h]”hÊ)”}”(hŒuCONFIG_MEM_ALLOC_PROFILING_DEBUG
adds warnings for allocations that weren't accounted because of a
missing annotation”h]”hŒwCONFIG_MEM_ALLOC_PROFILING_DEBUG
adds warnings for allocations that werenâ€™t accounted because of a
missing annotation”…””}”(hj
  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Khj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hìhhéhžhhŸh³h Nubeh}”(h]”h ]”h"]”h$]”h&]”Œbullet”Œ-”uh1hçhŸh³h Khh¶hžhubhŒdefinition_list”“”)”}”(hhh]”(hŒdefinition_list_item”“”)”}”(hX©  Boot parameter:
sysctl.vm.mem_profiling={0|1|never}[,compressed]

When set to "never", memory allocation profiling overhead is minimized and it
cannot be enabled at runtime (sysctl becomes read-only).
When CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=y, default value is "1".
When CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=n, default value is "never".
"compressed" optional parameter will try to store page tag references in a
compact format, avoiding page extensions. This results in improved performance
and memory consumption, however it might fail depending on system configuration.
If compression fails, a warning is issued and memory allocation profiling gets
disabled.
”h]”(hŒterm”“”)”}”(hŒBoot parameter:”h]”hŒBoot parameter:”…””}”(hj3  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j1  hŸh³h Khj-  ubhŒ
definition”“”)”}”(hhh]”(hÊ)”}”(hŒ0sysctl.vm.mem_profiling={0|1|never}[,compressed]”h]”hŒ0sysctl.vm.mem_profiling={0|1|never}[,compressed]”…””}”(hjF  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KhjC  ubhÊ)”}”(hXf  When set to "never", memory allocation profiling overhead is minimized and it
cannot be enabled at runtime (sysctl becomes read-only).
When CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=y, default value is "1".
When CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=n, default value is "never".
"compressed" optional parameter will try to store page tag references in a
compact format, avoiding page extensions. This results in improved performance
and memory consumption, however it might fail depending on system configuration.
If compression fails, a warning is issued and memory allocation profiling gets
disabled.”h]”hXv  When set to â€œneverâ€, memory allocation profiling overhead is minimized and it
cannot be enabled at runtime (sysctl becomes read-only).
When CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=y, default value is â€œ1â€.
When CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=n, default value is â€œneverâ€.
â€œcompressedâ€ optional parameter will try to store page tag references in a
compact format, avoiding page extensions. This results in improved performance
and memory consumption, however it might fail depending on system configuration.
If compression fails, a warning is issued and memory allocation profiling gets
disabled.”…””}”(hjT  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KhjC  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jA  hj-  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j+  hŸh³h Khj(  ubj,  )”}”(hŒ#sysctl:
/proc/sys/vm/mem_profiling
”h]”(j2  )”}”(hŒsysctl:”h]”hŒsysctl:”…””}”(hjr  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j1  hŸh³h K"hjn  ubjB  )”}”(hhh]”hÊ)”}”(hŒ/proc/sys/vm/mem_profiling”h]”hŒ/proc/sys/vm/mem_profiling”…””}”(hjƒ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K"hj€  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jA  hjn  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j+  hŸh³h K"hj(  hžhubj,  )”}”(hŒRuntime info:
/proc/allocinfo
”h]”(j2  )”}”(hŒRuntime info:”h]”hŒRuntime info:”…””}”(hj¡  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j1  hŸh³h K%hj  ubjB  )”}”(hhh]”hÊ)”}”(hŒ/proc/allocinfo”h]”hŒ/proc/allocinfo”…””}”(hj²  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K%hj¯  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jA  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j+  hŸh³h K%hj(  hžhubeh}”(h]”h ]”h"]”h$]”h&]”uh1j&  hh¶hžhhŸh³h NubhÊ)”}”(hŒExample output::”h]”hŒExample output:”…””}”(hjÒ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K'hh¶hžhubhŒliteral_block”“”)”}”(hX  root@moria-kvm:~# sort -g /proc/allocinfo|tail|numfmt --to=iec
      2.8M    22648 fs/kernfs/dir.c:615 func:__kernfs_new_node
      3.8M      953 mm/memory.c:4214 func:alloc_anon_folio
      4.0M     1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start
      4.1M        4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable
      6.0M     1532 mm/filemap.c:1919 func:__filemap_get_folio
      8.8M     2785 kernel/fork.c:307 func:alloc_thread_stack_node
       13M      234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs
       14M     3520 mm/mm_init.c:2530 func:alloc_large_system_hash
       15M     3656 mm/readahead.c:247 func:page_cache_ra_unbounded
       55M     4887 mm/slub.c:2259 func:alloc_slab_page
      122M    31168 mm/page_ext.c:270 func:alloc_page_ext”h]”hX  root@moria-kvm:~# sort -g /proc/allocinfo|tail|numfmt --to=iec
      2.8M    22648 fs/kernfs/dir.c:615 func:__kernfs_new_node
      3.8M      953 mm/memory.c:4214 func:alloc_anon_folio
      4.0M     1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start
      4.1M        4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable
      6.0M     1532 mm/filemap.c:1919 func:__filemap_get_folio
      8.8M     2785 kernel/fork.c:307 func:alloc_thread_stack_node
       13M      234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs
       14M     3520 mm/mm_init.c:2530 func:alloc_large_system_hash
       15M     3656 mm/readahead.c:247 func:page_cache_ra_unbounded
       55M     4887 mm/slub.c:2259 func:alloc_slab_page
      122M    31168 mm/page_ext.c:270 func:alloc_page_ext”…””}”hjâ  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jà  hŸh³h K)hh¶hžhubhµ)”}”(hhh]”(hº)”}”(hŒTheory of operation”h]”hŒTheory of operation”…””}”(hjó  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjð  hžhhŸh³h K7ubhÊ)”}”(hX'  Memory allocation profiling builds off of code tagging, which is a library for
declaring static structs (that typically describe a file and line number in
some way, hence code tagging) and then finding and operating on them at runtime,
- i.e. iterating over them to print them in debugfs/procfs.”h]”hX'  Memory allocation profiling builds off of code tagging, which is a library for
declaring static structs (that typically describe a file and line number in
some way, hence code tagging) and then finding and operating on them at runtime,
- i.e. iterating over them to print them in debugfs/procfs.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K9hjð  hžhubhÊ)”}”(hX  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.”h]”hX  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.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K>hjð  hžhubhÊ)”}”(hXX  This allows for alloc_hooks() calls to be nested, with the most recent one
taking effect. This is important for allocations internal to the mm/ code that
do not properly belong to the outer allocation context and should be counted
separately: for example, slab object extension vectors, or when the slab
allocates pages from the page allocator.”h]”hXX  This allows for alloc_hooks() calls to be nested, with the most recent one
taking effect. This is important for allocations internal to the mm/ code that
do not properly belong to the outer allocation context and should be counted
separately: for example, slab object extension vectors, or when the slab
allocates pages from the page allocator.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KEhjð  hžhubhÊ)”}”(hXV  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.”h]”hXX  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;
weâ€™ll generally want the accounting to happen in the callers of these helpers,
not in the helpers themselves.”…””}”(hj+  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KKhjð  hžhubhÊ)”}”(hŒ‹To fix up a given helper, for example foo(), do the following:
- switch its allocation call to the _noprof() version, e.g. kmalloc_noprof()”h]”hŒ‹To fix up a given helper, for example foo(), do the following:
- switch its allocation call to the _noprof() version, e.g. kmalloc_noprof()”…””}”(hj9  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KQhjð  hžhubhè)”}”(hhh]”(hí)”}”(hŒrename it to foo_noprof()
”h]”hÊ)”}”(hŒrename it to foo_noprof()”h]”hŒrename it to foo_noprof()”…””}”(hjN  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KThjJ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hìhjG  hžhhŸh³h Nubhí)”}”(hŒ`define a macro version of foo() like so:

#define foo(...) alloc_hooks(foo_noprof(__VA_ARGS__))
”h]”(hÊ)”}”(hŒ(define a macro version of foo() like so:”h]”hŒ(define a macro version of foo() like so:”…””}”(hjf  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KVhjb  ubhÊ)”}”(hŒ5#define foo(...) alloc_hooks(foo_noprof(__VA_ARGS__))”h]”hŒ5#define foo(...) alloc_hooks(foo_noprof(__VA_ARGS__))”…””}”(hjt  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KXhjb  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1hìhjG  hžhhŸh³h Nubeh}”(h]”h ]”h"]”h$]”h&]”j$  j%  uh1hçhŸh³h KThjð  hžhubhÊ)”}”(hŒRIt's also possible to stash a pointer to an alloc tag in your own data structures.”h]”hŒTItâ€™s also possible to stash a pointer to an alloc tag in your own data structures.”…””}”(hjŽ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KZhjð  hžhubhÊ)”}”(hX  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.”h]”hX  Do this when youâ€™re implementing a generic data structure that does allocations
â€œon behalf ofâ€ 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.”…””}”(hjœ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K\hjð  hžhubhÊ)”}”(hŒYTo do so:
- Hook your data structure's init function, like any other allocation function.”h]”hŒ[To do so:
- Hook your data structureâ€™s init function, like any other allocation function.”…””}”(hjª  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kahjð  hžhubhè)”}”(hhh]”(hí)”}”(hŒtWithin your init function, use the convenience macro alloc_tag_record() to
record alloc tag in your data structure.
”h]”hÊ)”}”(hŒsWithin your init function, use the convenience macro alloc_tag_record() to
record alloc tag in your data structure.”h]”hŒsWithin your init function, use the convenience macro alloc_tag_record() to
record alloc tag in your data structure.”…””}”(hj¿  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kdhj»  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hìhj¸  hžhhŸh³h Nubhí)”}”(hŒkThen, use the following form for your allocations:
alloc_hooks_tag(ht->your_saved_tag, kmalloc_noprof(...))”h]”hÊ)”}”(hŒkThen, use the following form for your allocations:
alloc_hooks_tag(ht->your_saved_tag, kmalloc_noprof(...))”h]”hŒkThen, use the following form for your allocations:
alloc_hooks_tag(ht->your_saved_tag, kmalloc_noprof(...))”…””}”(hj×  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KghjÓ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hìhj¸  hžhhŸh³h Nubeh}”(h]”h ]”h"]”h$]”h&]”j$  j%  uh1hçhŸh³h Kdhjð  hžhubeh}”(h]”Œtheory-of-operation”ah ]”h"]”Œtheory of operation”ah$]”h&]”uh1h´hh¶hžhhŸh³h K7ubeh}”(h]”Œmemory-allocation-profiling”ah ]”h"]”Œmemory allocation profiling”ah$]”h&]”uh1h´hhhžhhŸh³h Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”h³uh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(h¹NŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ	traceback”ˆŒinput_encoding”Œ	utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”j$  Œerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œlanguage_code”Œen”Œrecord_dependencies”NŒconfig”NŒ	id_prefix”hŒauto_id_prefix”Œid”Œdump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”h³Œ_destination”NŒ_config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'Œpep_references”NŒpep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒrfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ	tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œsmart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œdocinfo_xform”KŒsectsubtitle_xform”‰Œimage_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”(jþ  jû  jö  jó  uŒ	nametypes”}”(jþ  ‰jö  ‰uh}”(jû  h¶jó  jð  uŒfootnote_refs”}”Œcitation_refs”}”Œautofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ	footnotes”]”Œ	citations”]”Œautofootnote_start”KŒsymbol_footnote_start”K Œ
id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
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