On 09.08.24 11:05, Ryan Roberts wrote:
On 09/08/2024 09:58, David Hildenbrand wrote:
On 09.08.24 10:42, David Hildenbrand wrote:
Not sure I fully understand why David prefers to do the unaccounting at
free-time though? It feels unbalanced to me to increment when first mapped but
decrement when freed. Surely its safer to either use alloc/free or use first
map/last map?
If using alloc/free isn't there a THP constructor/destructor that prepares the
deferred list? (My memory may be failing me). Could we use that?
Additionally, if we wanted to extend (eventually) to track the number of shmem
and file mthps in additional counters, could we also account using similar folio
free-time hooks? If not, it might be an argument to account in rmap_unmap to be
consistent for all?
Again, see NR_FILE_THPS handling. No rmap over-complication please.
... not to mention that it is non-sensical to only count pageache folios that
are mapped to user space ;)
Yes, good point. I'll get back in my box. :)
Well, it was a valuable discussion!
anon folios in the swapcache are interesting: they are only "anon" after
we first mapped them (harder to change, but would be possible by using a
NULL mapping maybe, if really worth it; with memdesc that might turn out
interesting). But once they are anon, they will stay anon until actually
reclaimed -> freed.
--
Cheers,
David / dhildenb
