Re: [PATCH v2] mm/mempolicy: track page allocations per mempolicy

["Vlastimil Babka (SUSE)" <vbabka@kernel.org>]

On 3/13/26 07:14, JP Kobryn (Meta) wrote:
> On 3/12/26 10:07 PM, Huang, Ying wrote:
>> "JP Kobryn (Meta)" <jp.kobryn@linux.dev> writes:
>> 
>>> On 3/12/26 6:40 AM, Vlastimil Babka (SUSE) wrote:
>>>
>>> How about I change from per-policy hit/miss/foreign triplets to a single
>>> aggregated policy triplet (i.e. just 3 new counters which account for
>>> all policies)? They would follow the same hit/miss/foreign semantics
>>> already proposed (visible in quoted text above). This would still
>>> provide the otherwise missing signal of whether policy-driven
>>> allocations to a node are intentional or fallback.
>>>
>>> Note that I am also planning on moving the stats off of the memcg so the
>>> 3 new counters will be global per-node in response to similar feedback.
>> 
>> Emm, what's the difference between these newly added counters and the
>> existing numa_hit/miss/foreign counters?
> 
> The existing counters don't account for node masks in the policies that
> make use of them. An allocation can land on a node in the mask and still
> be considered a miss because it wasn't the preferred node.

That sounds like we could just a new counter e.g. numa_hit_preferred and
adjust definitions accordingly? Or some other variant that fills the gap?