RE:(2) [PATCH] vmscan: add trace events for lru_gen

From: 김재원
Date: Wed Sep 20 2023 - 03:50:11 EST

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In reply to: Steven Rostedt: "Re: [PATCH] vmscan: add trace events for lru_gen"
Next in thread: Steven Rostedt: "Re: (2) [PATCH] vmscan: add trace events for lru_gen"
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>On Tue, 19 Sep 2023 11:52:16 +0900
>Jaewon Kim <jaewon31.kim@xxxxxxxxxxx> wrote:
>
>> /*
>> * Now redefine the EM() and EMe() macros to map the enums to the strings
>> diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
>> index d2123dd960d5..e8f9d0452e89 100644
>> --- a/include/trace/events/vmscan.h
>> +++ b/include/trace/events/vmscan.h
>> @@ -327,6 +327,55 @@ TRACE_EVENT(mm_vmscan_lru_isolate,
>> __print_symbolic(__entry->lru, LRU_NAMES))
>> );
>>
>> +TRACE_EVENT(mm_vmscan_lru_gen_scan,
>> + TP_PROTO(int highest_zoneidx,
>> + int order,
>> + unsigned long nr_requested,
>> + unsigned long nr_scanned,
>> + unsigned long nr_skipped,
>> + unsigned long nr_taken,
>> + isolate_mode_t isolate_mode,
>> + int lru),
>
>This is a lot of parameter passing, can you consolidate it?
>
>(see below to where you call this)
>
>> +
>> + TP_ARGS(highest_zoneidx, order, nr_requested, nr_scanned, nr_skipped, nr_taken, isolate_mode, lru),
>> +
>> + TP_STRUCT__entry(
>> + __field(int, highest_zoneidx)
>> + __field(int, order)
>> + __field(unsigned long, nr_requested)
>> + __field(unsigned long, nr_scanned)
>> + __field(unsigned long, nr_skipped)
>> + __field(unsigned long, nr_taken)
>> + __field(unsigned int, isolate_mode)
>> + __field(int, lru)
>> + ),
>> +
>> + TP_fast_assign(
>> + __entry->highest_zoneidx = highest_zoneidx;
>> + __entry->order = order;
>> + __entry->nr_requested = nr_requested;
>> + __entry->nr_scanned = nr_scanned;
>> + __entry->nr_skipped = nr_skipped;
>> + __entry->nr_taken = nr_taken;
>> + __entry->isolate_mode = (__force unsigned int)isolate_mode;
>> + __entry->lru = lru;
>> + ),
>> +
>> + /*
>> + * classzone is previous name of the highest_zoneidx.
>> + * Reason not to change it is the ABI requirement of the tracepoint.
>> + */
>> + TP_printk("isolate_mode=%d classzone=%d order=%d nr_requested=%lu nr_scanned=%lu nr_skipped=%lu nr_taken=%lu lru=%s",
>> + __entry->isolate_mode,
>> + __entry->highest_zoneidx,
>> + __entry->order,
>> + __entry->nr_requested,
>> + __entry->nr_scanned,
>> + __entry->nr_skipped,
>> + __entry->nr_taken,
>> + __print_symbolic(__entry->lru, LRU_GEN_NAMES))
>> +);
>> +
>> TRACE_EVENT(mm_vmscan_write_folio,
>>
>> TP_PROTO(struct folio *folio),
>> @@ -437,6 +486,53 @@ TRACE_EVENT(mm_vmscan_lru_shrink_active,
>> show_reclaim_flags(__entry->reclaim_flags))
>> );
>>
>> +TRACE_EVENT(mm_vmscan_lru_gen_evict,
>> +
>> + TP_PROTO(int nid, unsigned long nr_reclaimed,
>> + struct reclaim_stat *stat, int priority, int file),
>> +
>> + TP_ARGS(nid, nr_reclaimed, stat, priority, file),
>> +
>> + TP_STRUCT__entry(
>> + __field(int, nid)
>
>On 64 bit architectures, this causes a 4 byte hole in the ring buffer
>layout. Please keep 32 bit size fields paired with other 32 bit size if
>possible. That is, move the above "int nid" down where it doesn't cause a
>long field to be 4 bytes away.
>
>> + __field(unsigned long, nr_reclaimed)
>> + __field(unsigned long, nr_dirty)
>> + __field(unsigned long, nr_writeback)
>> + __field(unsigned long, nr_congested)
>> + __field(unsigned long, nr_immediate)
>> + __field(unsigned int, nr_activate0)
>> + __field(unsigned int, nr_activate1)
>> + __field(unsigned long, nr_ref_keep)
>> + __field(unsigned long, nr_unmap_fail)
>
> __field(int, nid)
>
>here!
>
>> + __field(int, priority)
>> + __field(int, reclaim_flags)
>> + ),
>> +
>> + TP_fast_assign(
>> + __entry->nid = nid;
>> + __entry->nr_reclaimed = nr_reclaimed;
>> + __entry->nr_dirty = stat->nr_dirty;
>> + __entry->nr_writeback = stat->nr_writeback;
>> + __entry->nr_congested = stat->nr_congested;
>> + __entry->nr_immediate = stat->nr_immediate;
>> + __entry->nr_activate0 = stat->nr_activate[0];
>> + __entry->nr_activate1 = stat->nr_activate[1];
>> + __entry->nr_ref_keep = stat->nr_ref_keep;
>> + __entry->nr_unmap_fail = stat->nr_unmap_fail;
>> + __entry->priority = priority;
>> + __entry->reclaim_flags = trace_reclaim_flags(file);
>> + ),
>> +
>> + TP_printk("nid=%d nr_reclaimed=%ld nr_dirty=%ld nr_writeback=%ld nr_congested=%ld nr_immediate=%ld nr_activate_anon=%d nr_activate_file=%d nr_ref_keep=%ld nr_unmap_fail=%ld priority=%d flags=%s",
>> + __entry->nid, __entry->nr_reclaimed,
>> + __entry->nr_dirty, __entry->nr_writeback,
>> + __entry->nr_congested, __entry->nr_immediate,
>> + __entry->nr_activate0, __entry->nr_activate1,
>> + __entry->nr_ref_keep, __entry->nr_unmap_fail,
>> + __entry->priority,
>> + show_reclaim_flags(__entry->reclaim_flags))
>> +);
>> +
>> TRACE_EVENT(mm_vmscan_node_reclaim_begin,
>>
>> TP_PROTO(int nid, int order, gfp_t gfp_flags),
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index 6f13394b112e..cc10e3fb8fa2 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -5005,6 +5005,7 @@ static int scan_folios(struct lruvec *lruvec, struct scan_control *sc,
>> int sorted = 0;
>> int scanned = 0;
>> int isolated = 0;
>> + int skipped = 0;
>> int remaining = MAX_LRU_BATCH;
>> struct lru_gen_folio *lrugen = &lruvec->lrugen;
>> struct mem_cgroup *memcg = lruvec_memcg(lruvec);
>> @@ -5018,7 +5019,7 @@ static int scan_folios(struct lruvec *lruvec, struct scan_control *sc,
>>
>> for (i = MAX_NR_ZONES; i > 0; i--) {
>> LIST_HEAD(moved);
>> - int skipped = 0;
>> + int skipped_zone = 0;
>> int zone = (sc->reclaim_idx + i) % MAX_NR_ZONES;
>> struct list_head *head = &lrugen->folios[gen][type][zone];
>>
>> @@ -5040,16 +5041,17 @@ static int scan_folios(struct lruvec *lruvec, struct scan_control *sc,
>> isolated += delta;
>> } else {
>> list_move(&folio->lru, &moved);
>> - skipped += delta;
>> + skipped_zone += delta;
>> }
>>
>> - if (!--remaining || max(isolated, skipped) >= MIN_LRU_BATCH)
>> + if (!--remaining || max(isolated, skipped_zone) >= MIN_LRU_BATCH)
>> break;
>> }
>>
>> - if (skipped) {
>> + if (skipped_zone) {
>> list_splice(&moved, head);
>> - __count_zid_vm_events(PGSCAN_SKIP, zone, skipped);
>> + __count_zid_vm_events(PGSCAN_SKIP, zone, skipped_zone);
>> + skipped += skipped_zone;
>> }
>>
>> if (!remaining || isolated >= MIN_LRU_BATCH)
>> @@ -5065,6 +5067,10 @@ static int scan_folios(struct lruvec *lruvec, struct scan_control *sc,
>> __count_memcg_events(memcg, PGREFILL, sorted);
>> __count_vm_events(PGSCAN_ANON + type, isolated);
>>
>> + if (scanned)
>
>BTW, you can make this branch conditional with the trace event logic, so
>that it isn't tested when tracing is enabled. That is, remove the
> "if (scanned)" test and use TRACE_EVENT_CONDITION() as I show below.
>
>> + trace_mm_vmscan_lru_gen_scan(sc->reclaim_idx, sc->order,
>> + MAX_LRU_BATCH, scanned, skipped, isolated,
>> + sc->may_unmap ? 0 : ISOLATE_UNMAPPED, type);
>
>Why not pass the sc in to the trace event, and then do the assigning there?
>
>// use CONDITION to test scanned
>
>TRACE_EVENT_CONDITION(mm_vmscan_lru_gen_scan,
>
> TP_PROTO(struct scan_control *sc,
> unsigned long nr_requested,
> unsigned long nr_scanned,
> unsigned long nr_skipped,
> unsigned long nr_taken,
> int lru),
>
> TP_ARGS(...)
>
> TP_CONDITION(nr_scanned)
>
> TP_fast_assign(
> __entry->highest_zoneidx = sc->reclaim_idx;
> __entry->order = sc->order;
> __entry->nr_requested = nr_requested;
> __entry->nr_scanned = nr_scanned;
> __entry->nr_skipped = nr_skipped;
> __entry->nr_taken = nr_taken;
> __entry->isolate_mode = (__force unsigned int)(sc->may_unmap ? 0 : ISOLATE_UNMAPPED);
> __entry->lru = lru;
> ),
>
>Lots of parameters can be expensive to pass, as it requires more copying.
>
>-- Steve

Great. Thank you for your comment.

For the putting the struct scan_control *sc inside the trace,
I couldn't do that because struct scan_control is defined in mm/vmscan.c.
I think I should not move it to a seperate header file.

As you may expect, I just made this by copying the existing
trace_mm_vmscan_lru_isolate and trace_mm_vmscan_lru_shrink_inactive

I've tried to change like this.
Would this be good for you?

--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -327,7 +327,7 @@ TRACE_EVENT(mm_vmscan_lru_isolate,
__print_symbolic(__entry->lru, LRU_NAMES))
);

-TRACE_EVENT(mm_vmscan_lru_gen_scan,
+TRACE_EVENT_CONDITION(mm_vmscan_lru_gen_scan,
TP_PROTO(int highest_zoneidx,
int order,
unsigned long nr_requested,
@@ -339,6 +339,8 @@ TRACE_EVENT(mm_vmscan_lru_gen_scan,

TP_ARGS(highest_zoneidx, order, nr_requested, nr_scanned, nr_skipped, nr_taken, isolate_mode, lru),

+ TP_CONDITION(nr_scanned),
+
TP_STRUCT__entry(
__field(int, highest_zoneidx)
__field(int, order)
@@ -494,7 +496,6 @@ TRACE_EVENT(mm_vmscan_lru_gen_evict,
TP_ARGS(nid, nr_reclaimed, stat, priority, file),

TP_STRUCT__entry(
- __field(int, nid)
__field(unsigned long, nr_reclaimed)
__field(unsigned long, nr_dirty)
__field(unsigned long, nr_writeback)
@@ -504,6 +505,7 @@ TRACE_EVENT(mm_vmscan_lru_gen_evict,
__field(unsigned int, nr_activate1)
__field(unsigned long, nr_ref_keep)
__field(unsigned long, nr_unmap_fail)
+ __field(int, nid)
__field(int, priority)
__field(int, reclaim_flags)
),

--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -5131,10 +5131,9 @@ static int scan_folios(struct lruvec *lruvec, struct scan_control *sc,
__count_memcg_events(memcg, PGREFILL, sorted);
__count_vm_events(PGSCAN_ANON + type, isolated);

- if (scanned)
- trace_mm_vmscan_lru_gen_scan(sc->reclaim_idx, sc->order,
- MAX_LRU_BATCH, scanned, skipped, isolated,
- sc->may_unmap ? 0 : ISOLATE_UNMAPPED, type);
+ trace_mm_vmscan_lru_gen_scan(sc->reclaim_idx, sc->order, MAX_LRU_BATCH,
+ scanned, skipped, isolated,
+ sc->may_unmap ? 0 : ISOLATE_UNMAPPED, type);

>
>
>> /*
>> * There might not be eligible folios due to reclaim_idx. Check the
>> * remaining to prevent livelock if it's not making progress.
>> @@ -5194,6 +5200,8 @@ static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swap
>> retry:
>> reclaimed = shrink_folio_list(&list, pgdat, sc, &stat, false);
>> sc->nr_reclaimed += reclaimed;
>> + trace_mm_vmscan_lru_gen_evict(pgdat->node_id, reclaimed, &stat,
>> + sc->priority, type);
>>
>> list_for_each_entry_safe_reverse(folio, next, &list, lru) {
>> if (!folio_evictable(folio)) {
>

Next message: Andrew Jones: "Re: [PATCH 5/7] KVM: riscv: selftests: Add senvcfg register to get-reg-list test"
Previous message: Parav Pandit: "RE: [virtio-dev] Re: [virtio-comment] Re: [VIRTIO PCI PATCH v5 1/1] transport-pci: Add freeze_mode to virtio_pci_common_cfg"
In reply to: Steven Rostedt: "Re: [PATCH] vmscan: add trace events for lru_gen"
Next in thread: Steven Rostedt: "Re: (2) [PATCH] vmscan: add trace events for lru_gen"
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