Re: [PATCH 2/2] alloc_tag: skip pgalloc_tag_swap if profiling is disabled

[Suren Baghdasaryan]

On Thu, Dec 26, 2024 at 3:01 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Thu, 26 Dec 2024 13:16:39 -0800 Suren Baghdasaryan <surenb@xxxxxxxxxx> wrote:
>
> > When memory allocation profiling is disabled, there is no need to swap
> > allocation tags during migration. Skip it to avoid unnecessary overhead.
> >
> > Fixes: e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()")
> > Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
>
> Are these changes worth backporting?  Some indication of how much
> difference the patches make would help people understand why we're
> proposing a backport.

The first patch ("alloc_tag: avoid current->alloc_tag manipulations
when profiling is disabled") I think is worth backporting. It
eliminates about half of the regression for slab allocations when
profiling is disabled. The second one I couldn't really measure, so I
think it's not as important. Thanks!

>