diff options
| author | Kent Overstreet <kent.overstreet@gmail.com> | 2022-04-21 15:25:07 -0400 |
|---|---|---|
| committer | Kent Overstreet <kent.overstreet@linux.dev> | 2023-06-21 03:32:17 -0400 |
| commit | 4bcd243a12545f1e48f4d2328dc7943085055403 (patch) | |
| tree | d20e9ea87f9a0cc9f4e64911c554ea7fa6884cb1 | |
| parent | 4e09c1a9e752c08f2e944d3ef2de211a7239b2e2 (diff) | |
mm: Count requests to free & nr freed per shrinker
The next step in this patch series for improving debugging of shrinker
related issues: keep counts of number of objects we request to free vs.
actually freed, and prints them in shrinker_to_text().
Shrinkers won't necessarily free all objects requested for a variety of
reasons, but if the two counts are wildly different something is likely
amiss.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
| -rw-r--r-- | include/linux/shrinker.h | 3 | ||||
| -rw-r--r-- | mm/vmscan.c | 10 |
2 files changed, 12 insertions, 1 deletions
diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index c9d24d39462e..7c146ac8878f 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -86,6 +86,9 @@ struct shrinker { #endif /* objs pending delete, per node */ atomic_long_t *nr_deferred; + + atomic_long_t objects_requested_to_free; + atomic_long_t objects_freed; }; #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */ diff --git a/mm/vmscan.c b/mm/vmscan.c index ce93194e73dd..34ec91b44f90 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -773,7 +773,11 @@ void shrinker_to_text(struct seq_buf *out, struct shrinker *shrinker) struct shrink_control sc = { .gfp_mask = GFP_KERNEL, }; seq_buf_puts(out, shrinker->name); - seq_buf_printf(out, " objects: %lu\n", shrinker->count_objects(shrinker, &sc)); + seq_buf_putc(out, '\n'); + + seq_buf_printf(out, "objects: %lu\n", shrinker->count_objects(shrinker, &sc)); + seq_buf_printf(out, "requested to free: %lu\n", atomic_long_read(&shrinker->objects_requested_to_free)); + seq_buf_printf(out, "objects freed: %lu\n", atomic_long_read(&shrinker->objects_freed)); if (shrinker->to_text) { shrinker->to_text(out, shrinker); @@ -904,12 +908,16 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, unsigned long ret; unsigned long nr_to_scan = min(batch_size, total_scan); + atomic_long_add(nr_to_scan, &shrinker->objects_requested_to_free); + shrinkctl->nr_to_scan = nr_to_scan; shrinkctl->nr_scanned = nr_to_scan; ret = shrinker->scan_objects(shrinker, shrinkctl); if (ret == SHRINK_STOP) break; + freed += ret; + atomic_long_add(ret, &shrinker->objects_freed); count_vm_events(SLABS_SCANNED, shrinkctl->nr_scanned); total_scan -= shrinkctl->nr_scanned; |