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Wed, 16 Sep 2026 02:14:39 +0000 X-Mizu-Trace-ID: 7a9ac813747d9e7d X-Migadu-Flow: FLOW_OUT Date: Wed, 16 Sep 2026 10:14:31 +0800 From: Baoquan He To: Ridong Chen Cc: Steven Rostedt , Masami Hiramatsu , Andrew Morton , Johannes Weiner , Mathieu Desnoyers , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baolin Wang , David Hildenbrand , Michal Hocko , Lorenzo Stoakes , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, "open list:MEMORY MANAGEMENT - MGLRU (MULTI-GEN LRU)" , Ridong Chen Subject: Re: [PATCH v2 2/3] mm/mglru: add tracepoint for scan_folios() Message-ID: References: <20260911102939.2485750-1-ridong.chen@linux.dev> <20260911102939.2485750-3-ridong.chen@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Queue-Id: 4766B180003 X-Stat-Signature: pxr8dz8ngfm73he7hbzn3wkf9hzi99yc X-Rspamd-Server: rspam01 X-HE-Tag: 1789524891-273554 X-HE-Meta: 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 MdI0hUC1 aq0sMb66L/ixWuz5mfzDhEMAZLDKoCsY8OifGA5ZWmkRIle+C4jvjIPXepdcPhEerz7+yUGwLq3DwlLIBOSeRuuARMtF+V/l4w6hvFFTLjcJMfUbDXcxK0L0a+sFJ5GCZeujXUaroi74KBBj0BSBvVdqYfJy3qO17OSmIZZQxt0uJ9LOGpgQBddIIP4SffEQcVLnCEKv/HPMFJsGNAqH9COZMegtt04gpFVh4a6CnxAxs0bQnjmOB5c3AkXbPCO2Sk9ofw9lskTCZy+Z8M63wGEzsMbANu88+7cx6jWn1x9ByYn09Xug2QL9P+Sz7cyLhYqpXTRs+z3W5LNF3j3zgg588cg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 09/15/26 at 08:17pm, Ridong Chen wrote: > > > On 9/15/2026 7:14 PM, Baoquan He wrote: > > On 09/11/26 at 06:29pm, Ridong Chen wrote: > > > From: Ridong Chen > > ...snip... > > > --- > > > include/trace/events/vmscan.h | 63 +++++++++++++++++++++++++++++++++++ > > > mm/vmscan.c | 6 ++++ > > > 2 files changed, 69 insertions(+) > > > > > > diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h > > > index 8a872990b4be..5defa8f6719c 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(struct lruvec *lruvec, > > > + 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), > > > > Thank you for your review. > > > Do we need show nid? Guess phone vendor doesn't care about multi-NUMA > > system. > > > > Eh, nid is not an mglru-specific key. Since there are 12 elements here, it > can't be added here. Hmm, we print memcg_id but not nid, it may not be so clear. How do you differentiate several lruvec-s on one memcg? I am not very familiar with trace mechanism, do we have a element number limit? Imagine I only want to trace this function, now I can see memcg_id, zone_idex, while don't know node/lruvec, that's a little pitty. Just my personal opinion, I could miss anything. > > > > And I checked v1 thread, seems Steven suggested to move the two int to > > avoid extra padding. > > > > Yeah, I will update it. I updated v2 to fix Sashiko's issue, before Steven > had any comment. > > > > > + > > > + TP_ARGS(lruvec, 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) > > > + ), > > > + > > > + TP_fast_assign( > > > + __entry->memcg_id = mem_cgroup_id(lruvec_memcg(lruvec)); > > > + __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..67f59aa73fb9 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(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]); > > > > And seems Steven also suggested to calculate lru, max_seq, min_seq in > > TP_fast_assign() in v1 which could be missed. > > > > Thanks, I will update it following Steven's suggestions. > > > > 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; > > ), > > > > However, 'sc' is an internal structure, so sc->order cannot be accessed in > TP_fast_assign(), and I don't think it is worth making scan_control an > external structure just for this. Agree. > > > > > > *isolatedp = isolated; > > > return scanned; > > > -- > > > 2.34.1 > > > > > -- > Best regards > Ridong >