summaryrefslogtreecommitdiff
path: root/Documentation/filesystems
diff options
context:
space:
mode:
authorSuren Baghdasaryan <surenb@google.com>2025-09-15 16:02:24 -0700
committerAndrew Morton <akpm@linux-foundation.org>2025-09-21 14:22:36 -0700
commitb9e2f58ffb84afcbba7e66f96ca14f98e0e88f26 (patch)
tree182704c6b83fc9bab0927562c3953321bdb52238 /Documentation/filesystems
parent5e1953dc71af01fae3d6786e073892ef3eebc3d8 (diff)
alloc_tag: mark inaccurate allocation counters in /proc/allocinfo output
While rare, memory allocation profiling can contain inaccurate counters if slab object extension vector allocation fails. That allocation might succeed later but prior to that, slab allocations that would have used that object extension vector will not be accounted for. To indicate incorrect counters, "accurate:no" marker is appended to the call site line in the /proc/allocinfo output. Bump up /proc/allocinfo version to reflect the change in the file format and update documentation. Example output with invalid counters: allocinfo - version: 2.0 0 0 arch/x86/kernel/kdebugfs.c:105 func:create_setup_data_nodes 0 0 arch/x86/kernel/alternative.c:2090 func:alternatives_smp_module_add 0 0 arch/x86/kernel/alternative.c:127 func:__its_alloc accurate:no 0 0 arch/x86/kernel/fpu/regset.c:160 func:xstateregs_set 0 0 arch/x86/kernel/fpu/xstate.c:1590 func:fpstate_realloc 0 0 arch/x86/kernel/cpu/aperfmperf.c:379 func:arch_enable_hybrid_capacity_scale 0 0 arch/x86/kernel/cpu/amd_cache_disable.c:258 func:init_amd_l3_attrs 49152 48 arch/x86/kernel/cpu/mce/core.c:2709 func:mce_device_create accurate:no 32768 1 arch/x86/kernel/cpu/mce/genpool.c:132 func:mce_gen_pool_create 0 0 arch/x86/kernel/cpu/mce/amd.c:1341 func:mce_threshold_create_device [surenb@google.com: document new "accurate:no" marker] Fixes: 39d117e04d15 ("alloc_tag: mark inaccurate allocation counters in /proc/allocinfo output") [akpm@linux-foundation.org: simplification per Usama, reflow text] [akpm@linux-foundation.org: add newline to prevent docs warning, per Randy] Link: https://lkml.kernel.org/r/20250915230224.4115531-1-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: Usama Arif <usamaarif642@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: David Wang <00107082@163.com> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Sourav Panda <souravpanda@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/proc.rst13
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index 915a3e44bc12..6ffd04c736db 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -1009,6 +1009,19 @@ number, module (if originates from a loadable module) and the function calling
the allocation. The number of bytes allocated and number of calls at each
location are reported. The first line indicates the version of the file, the
second line is the header listing fields in the file.
+If file version is 2.0 or higher then each line may contain additional
+<key>:<value> pairs representing extra information about the call site.
+For example if the counters are not accurate, the line will be appended with
+"accurate:no" pair.
+
+Supported markers in v2:
+accurate:no
+
+ Absolute values of the counters in this line are not accurate
+ because of the failure to allocate memory to track some of the
+ allocations made at this location. Deltas in these counters are
+ accurate, therefore counters can be used to track allocation size
+ and count changes.
Example output.