The quilt patch titled
Subject: alloc_tag: avoid current->alloc_tag manipulations when profiling is disabled
has been removed from the -mm tree. Its filename was
alloc_tag-avoid-current-alloc_tag-manipulations-when-profiling-is-disabled.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Subject: alloc_tag: avoid current->alloc_tag manipulations when profiling is disabled
Date: Thu, 26 Dec 2024 13:16:38 -0800
When memory allocation profiling is disabled there is no need to update
current->alloc_tag and these manipulations add unnecessary overhead. Fix
the overhead by skipping these extra updates.
I ran comprehensive testing on Pixel 6 on Big, Medium and Little cores:
Overhead before fixes Overhead after fixes
slab alloc page alloc slab alloc page alloc
Big 6.21% 5.32% 3.31% 4.93%
Medium 4.51% 5.05% 3.79% 4.39%
Little 7.62% 1.82% 6.68% 1.02%
This is an allocation microbenchmark doing allocations in a tight loop.
Not a really realistic scenario and useful only to make performance
comparisons.
Link: https://lkml.kernel.org/r/20241226211639.1357704-1-surenb@xxxxxxxxxx
Fixes: b951aaff5035 ("mm: enable page allocation tagging")
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: David Wang <00107082@xxxxxxx>
Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: Zhenhua Huang <quic_zhenhuah@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/alloc_tag.h | 11 ++++++++---
lib/alloc_tag.c | 2 ++
2 files changed, 10 insertions(+), 3 deletions(-)
--- a/include/linux/alloc_tag.h~alloc_tag-avoid-current-alloc_tag-manipulations-when-profiling-is-disabled
+++ a/include/linux/alloc_tag.h
@@ -224,9 +224,14 @@ static inline void alloc_tag_sub(union c
#define alloc_hooks_tag(_tag, _do_alloc) \
({ \
- struct alloc_tag * __maybe_unused _old = alloc_tag_save(_tag); \
- typeof(_do_alloc) _res = _do_alloc; \
- alloc_tag_restore(_tag, _old); \
+ typeof(_do_alloc) _res; \
+ if (mem_alloc_profiling_enabled()) { \
+ struct alloc_tag * __maybe_unused _old; \
+ _old = alloc_tag_save(_tag); \
+ _res = _do_alloc; \
+ alloc_tag_restore(_tag, _old); \
+ } else \
+ _res = _do_alloc; \
_res; \
})
--- a/lib/alloc_tag.c~alloc_tag-avoid-current-alloc_tag-manipulations-when-profiling-is-disabled
+++ a/lib/alloc_tag.c
@@ -29,6 +29,8 @@ EXPORT_SYMBOL(_shared_alloc_tag);
DEFINE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT,
mem_alloc_profiling_key);
+EXPORT_SYMBOL(mem_alloc_profiling_key);
+
DEFINE_STATIC_KEY_FALSE(mem_profiling_compressed);
struct alloc_tag_kernel_section kernel_tags = { NULL, 0 };
_
Patches currently in -mm which might be from surenb@xxxxxxxxxx are
