"JP Kobryn (Meta)" <[email protected]> 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)" <[email protected]> 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.
> So if we applied the hit/miss/foreign semantics in this patch to the
> existing counters we would be mixing allocations that are in and out
> of policy, losing the accuracy.
>
> The new 3 counters I last proposed (in an effort to reduce the amount of
> new counters as much as possible) would isolate mempolicy allocs and be
> named to reflect that: numa_mpol_{hit,miss,foreign}.
---
Best Regards,
Huang, Ying
