On 15.11.24 15:41, Qi Zheng wrote:
On 2024/11/15 18:22, David Hildenbrand wrote:
*nr_skip = nr;
and then:
zap_pte_range
--> nr = do_zap_pte_range(tlb, vma, pte, addr, end, details, &skip_nr,
rss, &force_flush, &force_break);
if (can_reclaim_pt) {
none_nr += count_pte_none(pte, nr);
none_nr += nr_skip;
}
Right?
Yes. I did not look closely at the patch that adds the counting of
Got it.
pte_none though (to digest why it is required :) ).
Because 'none_nr == PTRS_PER_PTE' is used in patch #7 to detect
empty PTE page.
Okay, so the problem is that "nr" would be "all processed entries" but
there are cases where we "process an entry but not zap it".
What you really only want to know is "was any entry not zapped", which
could be a simple input boolean variable passed into do_zap_pte_range?
Because as soon as any entry was processed but no zapped, you can
immediately give up on reclaiming that table.
Yes, we can set can_reclaim_pt to false when a !pte_none() entry is
found in count_pte_none().
I'm not sure if well need cont_pte_none(), but I'll have to take a look
at your new patch to see how this fits together with doing the pte_none
detection+skipping in do_zap_pte_range().
I was wondering if you cannot simply avoid the additional scanning and
simply set "can_reclaim_pt" if you skip a zap.
--
Cheers,
David / dhildenb
