Re: [PATCH v2] mm/page_alloc: trace PCP refills and PCP zone lock usage

[SUVONOV BUNYOD <b.suvonov@sjtu.edu.cn>]

Thank you for reviewing v1 Vishal,

All of your concerns except for the last one should be covered in v2.

> If you're trying to trace all pages as they come onto the pcp lists,
> should you also account for the free_frozen_page_commit() path?
>
>>          }
>>          spin_unlock_irqrestore(&zone->lock, flags);

No, the intent is not to trace every insertion into PCP lists. This patch
is trying to make buddy <-> PCP traffic observable by adding a new
mm_page_pcpu_refill event symmetric with the existing mm_page_pcpu_drain
event.

I also added additional zone_locked tracepoints because my research is
focusing on analyzing which kernel mm subsystems and other parts are
under stress for a given workload. The best way to see it for PCP would
be to count zone lock acquirings as the whole purpose of PCP is to lower
number of zone lock acquiring in first place.