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

[Vlastimil Babka <vbabka@suse.cz>]

On 5/31/24 6:43 PM, Alexei Starovoitov wrote:
> On Fri, May 31, 2024 at 2:33 AM Vlastimil Babka <vbabka@suse.cz> wrote:
>>         might_alloc(flags);
>>
>> -       if (unlikely(should_failslab(s, flags)))
>> -               return NULL;
>> +       if (static_branch_unlikely(&should_failslab_active)) {
>> +               if (should_failslab(s, flags))
>> +                       return NULL;
>> +       }
> 
> makes sense.
> Acked-by: Alexei Starovoitov <ast@kernel.org>

Thanks :) but please note the cover letter where I explain how I need help
with the bpftrace side (and ftrace, but that seems sorted). Without that
part, bpftrace will silently stop doing the injection as the static key will
remain disabled.

> Do you have any microbenchmark numbers before/after this optimization?

Also in cover letter, but will include it in the patch commit log next time.