On 2024/7/23 21:03, Zi Yan wrote:
On Tue Jul 23, 2024 at 6:17 AM EDT, David Hildenbrand wrote:
On 23.07.24 05:24, Kefeng Wang wrote:
On 2024/7/23 9:54, Zi Yan wrote:
On Mon Jul 22, 2024 at 9:48 PM EDT, Kefeng Wang wrote:
On 2024/7/23 1:29, Zi Yan wrote:
memory tiering can be enabled/disabled at runtime and
sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING is used to check
it. In migrate_misplaced_folio(), the check is missing when
PGPROMOTE_SUCCESS is incremented. Add the missing check.
Reported-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-mm/f4ae2c9c-fe40-4807-bdb2-64cf2d716c1a@xxxxxxxxxx/
Fixes: 33024536bafd ("memory tiering: hot page selection with hint page fault latency")
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Reviewed-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Thanks.
---
mm/migrate.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index bdbb5bb04c91..b819809da470 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2630,7 +2630,9 @@ int migrate_misplaced_folio(struct folio *folio, struct vm_area_struct *vma,
putback_movable_pages(&migratepages);
if (nr_succeeded) {
count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
- if (!node_is_toptier(folio_nid(folio)) && node_is_toptier(node))
+ if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING)
+ && !node_is_toptier(folio_nid(folio))
+ && node_is_toptier(node))
mod_node_page_state(pgdat, PGPROMOTE_SUCCESS,
nr_succeeded);
The should be in advance of patch2, and change above to use
folio_has_cpupid() helper() too.
It shares the same logic of !folio_has_cpupid() but it might be confusing to
put !folio_has_cpupid(folio) && node_is_toptier(node) here. folio's
cpupid has nothing to do with the stats here, thus I did not use the
function.
If folio don't include access time, we do migrate it but it isn't a
promotion, so don't count it, other comments?
PS: Could we rename folio_has_cpupid() to folio_has_access_time(), even
without memory_tiering, we still have cpupid in folio, right?
folio_has_access_time() would be the opposite of folio_has_cpupid().
If memory tiering is off (either at compile time or dynamically), a
folio has cpupid all the time.
Maybe call it "folio_use_cpupid()" or sth like that? The "has" is a bit
misleading, because the folio has a cpuid in any case, no?
The folio's cpupid field is reused to record page access time, when the folio
is !node_is_toptier() and memory tiering mode is on.
In sum, using folio_use_access_time() as !folio_has_cpupid() seems
better to me, since it covers the special use of folio's cpupid field.
It sounds good, thanks.
Let me know your thoughts.
