On Fri, 11 Sep 2026 15:28:47 +0800
Ridong Chen <[email protected]> wrote:
> diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
> index 8a872990b4be..c39dfacef033 100644
> --- a/include/trace/events/vmscan.h
> +++ b/include/trace/events/vmscan.h
> @@ -392,6 +392,69 @@ TRACE_EVENT(mm_vmscan_lru_isolate,
> __print_symbolic(__entry->lru, LRU_NAMES))
> );
>
> +TRACE_EVENT(mm_mglru_scan_folios,
> +
> + TP_PROTO(u64 memcg_id,
> + int highest_zoneidx,
> + int order,
> + unsigned long nr_requested,
> + unsigned long nr_scanned,
> + unsigned long nr_sorted,
> + unsigned long nr_skipped,
> + unsigned long nr_taken,
> + int lru,
> + unsigned long max_seq,
> + int tier,
> + unsigned long min_seq),
> +
> + TP_ARGS(memcg_id, highest_zoneidx, order, nr_requested, nr_scanned,
> + nr_sorted, nr_skipped, nr_taken, lru, max_seq, tier, min_seq),
> +
> + TP_STRUCT__entry(
> + __field(u64, memcg_id)
> + __field(int, highest_zoneidx)
> + __field(int, order)
> + __field(unsigned long, nr_requested)
> + __field(unsigned long, nr_scanned)
> + __field(unsigned long, nr_sorted)
> + __field(unsigned long, nr_skipped)
> + __field(unsigned long, nr_taken)
> + __field(int, lru)
> + __field(unsigned long, max_seq)
> + __field(int, tier)
> + __field(unsigned long, min_seq)
Please keep "int"s together. This creates a structure that is used to write
into the ring buffer. On 64bit machines, the above would add 4 bytes of
padding after each int, whereas:
__field(unsigned long, max_seq)
__field(unsigned long, min_seq)
__field(int, lru)
__field(int, tier)
would not.
> + ),
> +
> + TP_fast_assign(
> + __entry->memcg_id = memcg_id;
> + __entry->highest_zoneidx = highest_zoneidx;
> + __entry->order = order;
> + __entry->nr_requested = nr_requested;
> + __entry->nr_scanned = nr_scanned;
> + __entry->nr_sorted = nr_sorted;
> + __entry->nr_skipped = nr_skipped;
> + __entry->nr_taken = nr_taken;
> + __entry->lru = lru;
> + __entry->max_seq = max_seq;
> + __entry->tier = tier;
> + __entry->min_seq = min_seq;
> + ),
> +
> + TP_printk("memcg_id=%llu classzone=%d order=%d nr_requested=%lu
> nr_scanned=%lu nr_sorted=%lu nr_skipped=%lu nr_taken=%lu lru=%s max_seq=%lu
> tier=%d min_seq=%lu",
> + __entry->memcg_id,
> + __entry->highest_zoneidx,
> + __entry->order,
> + __entry->nr_requested,
> + __entry->nr_scanned,
> + __entry->nr_sorted,
> + __entry->nr_skipped,
> + __entry->nr_taken,
> + __print_symbolic(__entry->lru, LRU_NAMES),
> + __entry->max_seq,
> + __entry->tier,
> + __entry->min_seq)
> +);
> +
> TRACE_EVENT(mm_vmscan_write_folio,
>
> TP_PROTO(struct folio *folio),
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 2554a6513aa8..bd1b9ecf2e84 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -4876,6 +4876,12 @@ static int scan_folios(unsigned long nr_to_scan,
> struct lruvec *lruvec,
> trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan,
> scanned, skipped, isolated,
> type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON);
> + trace_mm_mglru_scan_folios(mem_cgroup_id(lruvec_memcg(lruvec)),
> + sc->reclaim_idx, sc->order, nr_to_scan,
> + scanned, sorted, skipped, isolated,
> + type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON,
> + lrugen->max_seq, tier,
> + lrugen->min_seq[type]);
Can't this information be processed in the tracepoint? That is:
TP_PROTO(struct lruvec *lruvec,
struct scan_control *sc,
struct lru_gen_folio *lrugen,
unsigned long nr_requested,
unsigned long nr_scanned,
unsigned long nr_sorted,
unsigned long nr_skipped,
unsigned long nr_taken,
int type),
TP_ARGS(lruvec, sc, lrugen, nr_requested, nr_scanned,
nr_sorted, nr_skipped, nr_taken, type),
TP_STRUCT__entry(
__field(u64, memcg_id)
__field(int, highest_zoneidx)
__field(int, order)
__field(unsigned long, nr_requested)
__field(unsigned long, nr_scanned)
__field(unsigned long, nr_sorted)
__field(unsigned long, nr_skipped)
__field(unsigned long, nr_taken)
__field(unsigned long, max_seq)
__field(unsigned long, min_seq)
__field(int, lru)
__field(int, tier)
),
TP_fast_assign(
__entry->memcg_id = mem_cgroup_id(lruvec_memcg(lruvec));
__entry->highest_zoneidx = sc->reclaim_idx;
__entry->order = sc->order;
__entry->nr_requested = nr_requested;
__entry->nr_scanned = nr_scanned;
__entry->nr_sorted = nr_sorted;
__entry->nr_skipped = nr_skipped;
__entry->nr_taken = nr_taken;
__entry->lru = type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON;
__entry->max_seq = lrugen->max_seq;
__entry->tier = tier;
__entry->min_seq = lrugen->min_seq;
),
This moves the code to generate the parameters into the TP_fast_assign()
which is in a separate text section. It remove code from the work flow
improving instruction cache.
Same can be done for that trace_mm_vmscan_lru_isolate() trace event.
-- Steve
>
> *isolatedp = isolated;
> return scanned;
> --
