On 2024/11/15 05:19, David Hildenbrand wrote:
On 14.11.24 13:51, Qi Zheng wrote:
On 2024/11/14 20:32, David Hildenbrand wrote:
On 14.11.24 10:20, Qi Zheng wrote:
On 2024/11/14 16:04, David Hildenbrand wrote:
static unsigned long zap_pte_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end,
@@ -1682,13 +1704,17 @@ static unsigned long zap_pte_range(struct
mmu_gather *tlb,
pte_t ptent = ptep_get(pte);
int max_nr;
- nr = 1;
- if (pte_none(ptent))
- continue;
-
if (need_resched())
break;
+ nr = skip_none_ptes(pte, addr, end);
+ if (nr) {
+ addr += PAGE_SIZE * nr;
+ if (addr == end)
+ break;
+ pte += nr;
+ }
+
max_nr = (end - addr) / PAGE_SIZE;
I dislike calculating max_nr twice, once here and once in
skip_non_ptes.
Further, you're missing to update ptent here.
Oh, my bad. However, with [PATCH v3 5/9], there will be no problem, but
there are still two ptep_get() and max_nr calculation.
If you inline it you can
avoid another ptep_get().
Do you mean to inline the skip_none_ptes() into do_zap_pte_range()?
Effectively moving this patch after #5, and have it be something like:
diff --git a/mm/memory.c b/mm/memory.c
index 1949f5e0fece5..4f5d1e4c6688e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1667,8 +1667,21 @@ static inline int do_zap_pte_range(struct
mmu_gather *tlb,
pte_t ptent = ptep_get(pte);
int max_nr = (end - addr) / PAGE_SIZE;
- if (pte_none(ptent))
- return 1;
+ /* Skip all consecutive pte_none(). */
+ if (pte_none(ptent)) {
+ int nr;
+
+ for (nr = 1; nr < max_nr; nr++) {
+ ptent = ptep_get(pte + nr);
+ if (!pte_none(ptent))
+ break;
+ }
+ max_nr -= nr;
+ if (!max_nr)
+ return nr;
+ pte += nr;
+ addr += nr * PAGE_SIZE;
+ }
if (pte_present(ptent))
return zap_present_ptes(tlb, vma, pte, ptent, max_nr,
In the context of this patch this makes most sense.
Regarding "count_pte_none" comment, I assume you talk about patch #7.
Yes.
Can't you simply return the number of pte_none that you skipped here
using another
input variable, if really required?
Suppose we add an input variable nr_skip to do_zap_pte_range(), you mean
to return the above nr to zap_pte_range() through:
Maybe "cur_none_nr" or something similar.
OK.
*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.
Looking forward to your more review feedback on this series.
Thanks!
