Re: [PATCH 2/2] mm: compaction.c: Add/Modify direct compaction tracepoints

[Vlastimil Babka]

On 07/27/2016 04:51 PM, Janani Ravichandran wrote:
Add zone information to an existing tracepoint in compact_zone(). Also,
add a new tracepoint at the end of the compaction code so that latency
information can be derived.
Signed-off-by: Janani Ravichandran <janani.rvchn...@gmail.com>
---
 include/trace/events/compaction.h | 38 +++++++++++++++++++++++++++++++++-----
 mm/compaction.c                   |  6 ++++--
 2 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/include/trace/events/compaction.h 
b/include/trace/events/compaction.h
index 36e2d6f..4d86769 100644
--- a/include/trace/events/compaction.h
+++ b/include/trace/events/compaction.h
@@ -158,12 +158,15 @@ TRACE_EVENT(mm_compaction_migratepages,
 );

 TRACE_EVENT(mm_compaction_begin,
-       TP_PROTO(unsigned long zone_start, unsigned long migrate_pfn,
-               unsigned long free_pfn, unsigned long zone_end, bool sync),
+       TP_PROTO(struct zone *zone, unsigned long zone_start,
+               unsigned long migrate_pfn, unsigned long free_pfn,
+               unsigned long zone_end, bool sync),

-       TP_ARGS(zone_start, migrate_pfn, free_pfn, zone_end, sync),
+       TP_ARGS(zone, zone_start, migrate_pfn, free_pfn, zone_end, sync),

        TP_STRUCT__entry(
+               __field(int, nid)
+               __field(int, zid)
                __field(unsigned long, zone_start)
                __field(unsigned long, migrate_pfn)
                __field(unsigned long, free_pfn)
@@ -172,6 +175,8 @@ TRACE_EVENT(mm_compaction_begin,
        ),

        TP_fast_assign(
+               __entry->nid = zone_to_nid(zone);
+               __entry->zid = zone_idx(zone);
                __entry->zone_start = zone_start;
                __entry->migrate_pfn = migrate_pfn;
                __entry->free_pfn = free_pfn;
@@ -179,7 +184,9 @@ TRACE_EVENT(mm_compaction_begin,
                __entry->sync = sync;
        ),

-       TP_printk("zone_start=0x%lx migrate_pfn=0x%lx free_pfn=0x%lx zone_end=0x%lx, 
mode=%s",
+       TP_printk("nid=%d zid=%d zone_start=0x%lx migrate_pfn=0x%lx free_pfn=0x%lx 
zone_end=0x%lx, mode=%s",

Yea, this tracepoint has been odd in not printing node/zone in a 
friendly way (it's possible to determine it from zone_start/zone_end 
though, so this is good in general. But instead of printing nid and zid 
like this, it would be nice to unify the output with the other 
tracepoints, e.g.:

DECLARE_EVENT_CLASS(mm_compaction_suitable_template,
[...]
        TP_printk("node=%d zone=%-8s order=%d ret=%s",
                __entry->nid,
                __print_symbolic(__entry->idx, ZONE_TYPE),

Thanks,
Vlastimil