Re:Performance regression in ip_set_swap on 6.7.0

["David Wang" <00107082@163.com>]

At 2024-01-14 02:24:07, "Jozsef Kadlecsik" <kadlec@blackhole.kfki.hu> wrote:
>On Thu, 11 Jan 2024, David Wang wrote:
>
>> I tested the patch with code stressing swap->destroy->create->add 10000 
>> times, the performance regression still happens, and now it is 
>> ip_set_destroy. (I pasted the test code at the end of this mail)

>> 
>> They all call wait_for_completion, which may sleep on something on 
>> purpose, I guess...
>
>That's OK because ip_set_destroy() calls rcu_barrier() which is needed to 
>handle flush in list type of sets.
>
>However, rcu_barrier() with call_rcu() together makes multiple destroys 
>one after another slow. But rcu_barrier() is needed for list type of sets 
>only and that can be handled separately. So could you test the patch 
>below? According to my tests it is even a little bit faster than the 
>original code before synchronize_rcu() was added to swap.

Confirmed~! This patch does fix the performance regression in my case.

Hope it can fix ale.crismani@automattic.com's original issue.



Thanks~
David