On 3/16/26 11:44 PM, Huang, Ying wrote:
"JP Kobryn (Meta)" <[email protected]> writes:
On 3/15/26 7:54 PM, Huang, Ying wrote:
"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.
I'm not seeing that. zone_statistics() is eventually reached.
alloc_pages_mpol() is not.
Yes. The page isn't allocated through alloc_pages_mpol(). For example,
if we want to allocate pages for the kernel instead of user space
applications. However, IMHO, the equivalent memory policy is
MPOL_LOCAL, that is, allocate from local node firstly, then fallback to
other nodes. I don't think that alloc_pages_mpol() is so special.
Sure. My response was based on how you said, "the default memory policy
is used here". I took that literally. I agree on the behavioral
equivalence, but the important point is that no mempolicy is set. In the
v3 patch which was recently sent out, I'm using that aspect to
distinguish between allocations with a user-defined mempolicy and
allocations without one.
