Re: [PATCH v2 3/3] memory tiering: count PGPROMOTE_SUCCESS when mem tiering is enabled.

["Zi Yan" <ziy@nvidia.com>]

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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@huawei.com>
> > Closes: https://lore.kernel.org/linux-mm/f4ae2c9c-fe40-4807-bdb2-64cf2d716c1a@huawei.com/
> > Fixes: 33024536bafd ("memory tiering: hot page selection with hint page fault latency")
> > Signed-off-by: Zi Yan <ziy@nvidia.com>
>
> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
>
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.

-- 
Best Regards,
Yan, Zi


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