On 12/20/2016 02:01 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@xxxxxxxx>
>
> Higher order requests oom debugging is currently quite hard. We do have
> some compaction points which can tell us how the compaction is operating
> but there is no trace point to tell us about compaction retry logic.
> This patch adds a one which will have the following format
>
> bash-3126 [001] .... 1498.220001: compact_retry: order=9 priority=COMPACT_PRIO_SYNC_LIGHT compaction_result=withdrawn retries=0 max_retries=16 should_retry=0
>
> we can see that the order 9 request is not retried even though we are in
> the highest compaction priority mode becase the last compaction attempt
> was withdrawn. This means that compaction_zonelist_suitable must have
> returned false and there is no suitable zone to compact for this request
> and so no need to retry further.
>
> another example would be
> <...>-3137 [001] .... 81.501689: compact_retry: order=9 priority=COMPACT_PRIO_SYNC_LIGHT compaction_result=failed retries=0 max_retries=16 should_retry=0
>
> in this case the order-9 compaction failed to find any suitable
> block. We do not retry anymore because this is a costly request
> and those do not go below COMPACT_PRIO_SYNC_LIGHT priority.
>
> Changes since v1
> - fix compaction_result into highlevel constants translation as per
> Vlastimil
>
> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Hmm I've noticed that I didn't suggest the following below here,
although I did for the vmscan tracepoints now. How about adding this
-fix for consistency?
--------8<--------
From: Vlastimil Babka <vbabka@xxxxxxx>
Date: Wed, 4 Jan 2017 11:44:09 +0100
Subject: [PATCH] oom, trace: add compaction retry tracepoint-fix
Let's print the compaction priorities lower-case and without
prefix for consistency.
Also indent fix in compact_result_to_feedback().
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
include/trace/events/mmflags.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index aa4caa6914a9..e4c3a0febcce 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -195,7 +195,7 @@ IF_HAVE_VM_SOFTDIRTY(VM_SOFTDIRTY, "softdirty" ) \
#define compact_result_to_feedback(result) \
({ \
- enum compact_result __result = result; \
+ enum compact_result __result = result; \
(compaction_failed(__result)) ? COMPACTION_FAILED : \
(compaction_withdrawn(__result)) ? COMPACTION_WITHDRAWN : COMPACTION_PROGRESS; \
})
@@ -206,9 +206,9 @@ IF_HAVE_VM_SOFTDIRTY(VM_SOFTDIRTY, "softdirty" ) \
EMe(COMPACTION_PROGRESS, "progress")
#define COMPACTION_PRIORITY \
- EM(COMPACT_PRIO_SYNC_FULL, "COMPACT_PRIO_SYNC_FULL") \
- EM(COMPACT_PRIO_SYNC_LIGHT, "COMPACT_PRIO_SYNC_LIGHT") \
- EMe(COMPACT_PRIO_ASYNC, "COMPACT_PRIO_ASYNC")
+ EM(COMPACT_PRIO_SYNC_FULL, "sync_full") \
+ EM(COMPACT_PRIO_SYNC_LIGHT, "sync_light") \
+ EMe(COMPACT_PRIO_ASYNC, "async")
#else
#define COMPACTION_STATUS
#define COMPACTION_PRIORITY
--
2.11.0
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