Hi Alex,
I think it would better to have the 90% under utilization threshold for
shrinker to be defined as macro rather than hard coded?
like,
/*
* The threshold to determine if thp is under utilized and can be
* shrunk.
*/
#define THP_NRML_UTILIZED_BUCKET THP_UTIL_BUCKET_NR - 1
This way, it is more clear.
--skip
> +bool can_shrink_thp(struct folio *folio)
> +{
> + int bucket, num_utilized_pages;
> +
> + if (!folio || !folio_test_anon(folio) || !folio_test_transhuge(folio))
> + return false;
> +
> + num_utilized_pages = thp_number_utilized_pages(folio);
> + bucket = thp_utilization_bucket(num_utilized_pages);
> +
> + return bucket >= 0 && bucket < THP_UTIL_BUCKET_NR - 1;
This can be
return bucket >= 0 && bucket < THP_NRML_UTILIZED_BUCKET;
> +}
> +
> static void thp_scan_next_zone(void)
> {
> struct timespec64 current_time;
> @@ -170,6 +183,9 @@ static void thp_util_scan(unsigned long pfn_end)
> if (bucket < 0)
> continue;
>
> + if (bucket < THP_UTIL_BUCKET_NR - 1)
Similarly, this one.
There might be other instances too.
> + add_underutilized_thp(page);
> +
> thp_scan.buckets[bucket].nr_thps++;
> thp_scan.buckets[bucket].nr_zero_pages += (HPAGE_PMD_NR - num_utilized_pages);
> }
> --
> 2.30.2
