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

["JP Kobryn (Meta)" <jp.kobryn@linux.dev>]

On 3/15/26 7:54 PM, Huang, Ying wrote:
> "JP Kobryn (Meta)" <jp.kobryn@linux.dev> writes:
> 
>> On 3/13/26 12:34 AM, Vlastimil Babka (SUSE) wrote:
>>> 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?
>>
>> It's an interesting thought. Looking into these existing counters more,
>> the in-kernel direct node allocations, which don't fall under any
>> mempolicy, are also included in these stats. One good example might be
>> include/linux/skbuff.h, where __dev_alloc_pages() calls
>> alloc_pages_node_noprof(NUMA_NO_NODE, ...) which eventually reaches
>> zone_statistics() and increments the stats.
> 
> IIUC, the default memory policy is used here, that is, MPOL_LOCAL.

I'm not seeing that. zone_statistics() is eventually reached.
alloc_pages_mpol() is not.