On Thu, Dec 26, 2024 at 4:43 PM Kent Overstreet
<kent.overstreet@xxxxxxxxx> wrote:
>
> On Thu, Dec 26, 2024 at 01:16:38PM -0800, Suren Baghdasaryan wrote:
> > 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 did it the other way because I was concerned about the overhead of
> adding a huge number of static keys. But on further thought a static key
> probably isn't any bigger than an alloc tag, no?
Hmm but a call
>
> >
> > Fixes: b951aaff5035 ("mm: enable page allocation tagging")
> > Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
> > ---
> > include/linux/alloc_tag.h | 11 ++++++++---
> > lib/alloc_tag.c | 2 ++
> > 2 files changed, 10 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h
> > index 0bbbe537c5f9..a946e0203e6d 100644
> > --- a/include/linux/alloc_tag.h
> > +++ b/include/linux/alloc_tag.h
> > @@ -224,9 +224,14 @@ static inline void alloc_tag_sub(union codetag_ref *ref, size_t bytes) {}
> >
> > #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; \
> > })
> >
> > diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> > index 7dcebf118a3e..4c373f444eb1 100644
> > --- a/lib/alloc_tag.c
> > +++ b/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 };
> >
> > base-commit: 431614f1580a03c1a653340c55ea76bd12a9403f
> > --
> > 2.47.1.613.gc27f4b7a9f-goog
> >
