Re: [PATCH 2/3] mm/mglru: add tracepoint for scan_folios()
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2026-09-11 14:10:09
Also in:
linux-mm, lkml
On Fri, 11 Sep 2026 15:28:47 +0800 Ridong Chen [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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.
quoted hunk ↗ jump to hunk
+ ), + + 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; --