Re: [PATCH RFC 3/4] mm, slab: add static key for should_failslab()

[Roman Gushchin]

On Fri, May 31, 2024 at 11:33:34AM +0200, Vlastimil Babka wrote:
> Since commit 4f6923fbb352 ("mm: make should_failslab always available for
> fault injection") should_failslab() is unconditionally a noinline
> function. This adds visible overhead to the slab allocation hotpath,
> even if the function is empty. With CONFIG_FAILSLAB=y there's additional
> overhead when the functionality is not enabled by a boot parameter or
> debugfs.
> 
> The overhead can be eliminated with a static key around the callsite.
> Fault injection and error injection frameworks can now be told that the
> this function has a static key associated, and are able to enable and
> disable it accordingly.
> 
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>

Reviewed-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>