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    SubjectRe: [PATCH v2 4/5] mm/compaction: more trace to understand when/why compaction start/finish
    On 01/12/2015 09:21 AM, Joonsoo Kim wrote:
    > It is not well analyzed that when/why compaction start/finish or not. With
    > these new tracepoints, we can know much more about start/finish reason of
    > compaction. I can find following bug with these tracepoint.
    >
    > http://www.spinics.net/lists/linux-mm/msg81582.html
    >
    > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    > ---
    > include/linux/compaction.h | 3 ++
    > include/trace/events/compaction.h | 94 +++++++++++++++++++++++++++++++++++++
    > mm/compaction.c | 41 ++++++++++++++--
    > 3 files changed, 134 insertions(+), 4 deletions(-)
    >
    > diff --git a/include/linux/compaction.h b/include/linux/compaction.h
    > index a9547b6..d82181a 100644
    > --- a/include/linux/compaction.h
    > +++ b/include/linux/compaction.h
    > @@ -12,6 +12,9 @@
    > #define COMPACT_PARTIAL 3
    > /* The full zone was compacted */
    > #define COMPACT_COMPLETE 4
    > +/* For more detailed tracepoint output */
    > +#define COMPACT_NO_SUITABLE_PAGE 5
    > +#define COMPACT_NOT_SUITABLE_ZONE 6
    > /* When adding new state, please change compaction_status_string, too */
    >
    > /* Used to signal whether compaction detected need_sched() or lock contention */
    > diff --git a/include/trace/events/compaction.h b/include/trace/events/compaction.h
    > index 139020b..839dd4f 100644
    > --- a/include/trace/events/compaction.h
    > +++ b/include/trace/events/compaction.h
    > @@ -164,6 +164,100 @@ TRACE_EVENT(mm_compaction_end,
    > compaction_status_string[__entry->status])
    > );
    >
    > +TRACE_EVENT(mm_compaction_try_to_compact_pages,
    > +
    > + TP_PROTO(
    > + int order,
    > + gfp_t gfp_mask,
    > + enum migrate_mode mode,
    > + int alloc_flags,
    > + int classzone_idx),

    I wonder if alloc_flags and classzone_idx is particularly useful. It affects the
    watermark checks, but those are a bit of blackbox anyway.

    > + TP_ARGS(order, gfp_mask, mode, alloc_flags, classzone_idx),
    > +
    > + TP_STRUCT__entry(
    > + __field(int, order)
    > + __field(gfp_t, gfp_mask)
    > + __field(enum migrate_mode, mode)
    > + __field(int, alloc_flags)
    > + __field(int, classzone_idx)
    > + ),
    > +
    > + TP_fast_assign(
    > + __entry->order = order;
    > + __entry->gfp_mask = gfp_mask;
    > + __entry->mode = mode;
    > + __entry->alloc_flags = alloc_flags;
    > + __entry->classzone_idx = classzone_idx;
    > + ),
    > +
    > + TP_printk("order=%d gfp_mask=0x%x mode=%d alloc_flags=0x%x classzone_idx=%d",
    > + __entry->order,
    > + __entry->gfp_mask,
    > + (int)__entry->mode,
    > + __entry->alloc_flags,
    > + __entry->classzone_idx)
    > +);
    > +
    > +DECLARE_EVENT_CLASS(mm_compaction_suitable_template,
    > +
    > + TP_PROTO(struct zone *zone,
    > + int order,
    > + int alloc_flags,
    > + int classzone_idx,
    > + int ret),
    > +
    > + TP_ARGS(zone, order, alloc_flags, classzone_idx, ret),
    > +
    > + TP_STRUCT__entry(
    > + __field(int, nid)
    > + __field(char *, name)
    > + __field(int, order)
    > + __field(int, alloc_flags)
    > + __field(int, classzone_idx)
    > + __field(int, ret)
    > + ),
    > +
    > + TP_fast_assign(
    > + __entry->nid = zone_to_nid(zone);
    > + __entry->name = (char *)zone->name;
    > + __entry->order = order;
    > + __entry->alloc_flags = alloc_flags;
    > + __entry->classzone_idx = classzone_idx;
    > + __entry->ret = ret;
    > + ),
    > +
    > + TP_printk("node=%d zone=%-8s order=%d alloc_flags=0x%x classzone_idx=%d ret=%s",
    > + __entry->nid,
    > + __entry->name,
    > + __entry->order,
    > + __entry->alloc_flags,
    > + __entry->classzone_idx,
    > + compaction_status_string[__entry->ret])
    > +);
    > +
    > +DEFINE_EVENT(mm_compaction_suitable_template, mm_compaction_finished,
    > +
    > + TP_PROTO(struct zone *zone,
    > + int order,
    > + int alloc_flags,
    > + int classzone_idx,
    > + int ret),
    > +
    > + TP_ARGS(zone, order, alloc_flags, classzone_idx, ret)
    > +);
    > +
    > +DEFINE_EVENT(mm_compaction_suitable_template, mm_compaction_suitable,
    > +
    > + TP_PROTO(struct zone *zone,
    > + int order,
    > + int alloc_flags,
    > + int classzone_idx,
    > + int ret),
    > +
    > + TP_ARGS(zone, order, alloc_flags, classzone_idx, ret)
    > +);
    > +
    > #endif /* _TRACE_COMPACTION_H */
    >
    > /* This part must be outside protection */
    > diff --git a/mm/compaction.c b/mm/compaction.c
    > index be28469..7500f01 100644
    > --- a/mm/compaction.c
    > +++ b/mm/compaction.c
    > @@ -25,6 +25,8 @@ char *compaction_status_string[] = {
    > "continue",
    > "partial",
    > "complete",
    > + "no_suitable_page",
    > + "not_suitable_zone",
    > };
    >
    > static inline void count_compact_event(enum vm_event_item item)
    > @@ -1048,7 +1050,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
    > return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
    > }
    >
    > -static int compact_finished(struct zone *zone, struct compact_control *cc,
    > +static int __compact_finished(struct zone *zone, struct compact_control *cc,
    > const int migratetype)
    > {
    > unsigned int order;
    > @@ -1103,7 +1105,21 @@ static int compact_finished(struct zone *zone, struct compact_control *cc,
    > return COMPACT_PARTIAL;
    > }
    >
    > - return COMPACT_CONTINUE;
    > + return COMPACT_NO_SUITABLE_PAGE;
    > +}
    > +
    > +static int compact_finished(struct zone *zone, struct compact_control *cc,
    > + const int migratetype)
    > +{
    > + int ret;
    > +
    > + ret = __compact_finished(zone, cc, migratetype);
    > + trace_mm_compaction_finished(zone, cc->order, cc->alloc_flags,
    > + cc->classzone_idx, ret);
    > + if (ret == COMPACT_NO_SUITABLE_PAGE)
    > + ret = COMPACT_CONTINUE;
    > +
    > + return ret;
    > }
    >
    > /*
    > @@ -1113,7 +1129,7 @@ static int compact_finished(struct zone *zone, struct compact_control *cc,
    > * COMPACT_PARTIAL - If the allocation would succeed without compaction
    > * COMPACT_CONTINUE - If compaction should run now
    > */
    > -unsigned long compaction_suitable(struct zone *zone, int order,
    > +static unsigned long __compaction_suitable(struct zone *zone, int order,
    > int alloc_flags, int classzone_idx)
    > {
    > int fragindex;
    > @@ -1157,11 +1173,25 @@ unsigned long compaction_suitable(struct zone *zone, int order,
    > */
    > fragindex = fragmentation_index(zone, order);
    > if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
    > - return COMPACT_SKIPPED;
    > + return COMPACT_NOT_SUITABLE_ZONE;
    >
    > return COMPACT_CONTINUE;
    > }
    >
    > +unsigned long compaction_suitable(struct zone *zone, int order,
    > + int alloc_flags, int classzone_idx)
    > +{
    > + unsigned long ret;
    > +
    > + ret = __compaction_suitable(zone, order, alloc_flags, classzone_idx);
    > + trace_mm_compaction_suitable(zone, order, alloc_flags,
    > + classzone_idx, ret);
    > + if (ret == COMPACT_NOT_SUITABLE_ZONE)
    > + ret = COMPACT_SKIPPED;
    > +
    > + return ret;
    > +}
    > +
    > static int compact_zone(struct zone *zone, struct compact_control *cc)
    > {
    > int ret;
    > @@ -1377,6 +1407,9 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
    > if (!order || !may_enter_fs || !may_perform_io)
    > return COMPACT_SKIPPED;
    >
    > + trace_mm_compaction_try_to_compact_pages(order, gfp_mask, mode,
    > + alloc_flags, classzone_idx);
    > +
    > /* Compact each zone in the list */
    > for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
    > nodemask) {
    >



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