On Wed 04-01-17 11:47:56, Vlastimil Babka wrote:
> 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 bash-3126 [001] .... 1498.220001: compact_retry: order=9 priority=COMPACT_PRIO_SYNC_LIGHT compaction_result=withdrawn retries=0 max_retries=16 should_retry=0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 was withdrawn.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>
I would just worry that c&p constant name is easier to work with when
vim -t $PRIO or git grep $PRIO. But if the lowercase and shorter sounds
better to you then no objections from me.
> ---
> 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
>
--
Michal Hocko
SUSE Labs
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