Messages in this thread | | | Subject | Re: [PATCH 3/3] oom, trace: add compaction retry tracepoint | From | Vlastimil Babka <> | Date | Thu, 15 Dec 2016 09:18:05 +0100 |
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On 12/14/2016 07:11 PM, Michal Hocko wrote: > On Wed 14-12-16 18:28:38, Vlastimil Babka wrote: >> On 12/14/2016 03:53 PM, Michal Hocko wrote: >>> From: Michal Hocko <mhocko@suse.com> >>> >>> 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 bash-3126 [001] .... 1498.220001: compact_retry: order=9 priority=COMPACT_PRIO_SYNC_LIGHT compaction_result=withdrawn retries=0 max_retries=16 should_retry=0 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 was withdrawn.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. >>> >>> Signed-off-by: Michal Hocko <mhocko@suse.com> >>> --- >>> include/trace/events/mmflags.h | 26 ++++++++++++++++++++++++++ >>> include/trace/events/oom.h | 39 +++++++++++++++++++++++++++++++++++++++ >>> mm/page_alloc.c | 22 ++++++++++++++++------ >>> 3 files changed, 81 insertions(+), 6 deletions(-) >>> >>> diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h >>> index 7e4cfede873c..aa4caa6914a9 100644 >>> --- a/include/trace/events/mmflags.h >>> +++ b/include/trace/events/mmflags.h >>> @@ -187,8 +187,32 @@ IF_HAVE_VM_SOFTDIRTY(VM_SOFTDIRTY, "softdirty" ) \ >>> EM( COMPACT_NO_SUITABLE_PAGE, "no_suitable_page") \ >>> EM( COMPACT_NOT_SUITABLE_ZONE, "not_suitable_zone") \ >>> EMe(COMPACT_CONTENDED, "contended") >>> + >>> +/* High-level compaction status feedback */ >>> +#define COMPACTION_FAILED 1 >>> +#define COMPACTION_WITHDRAWN 2 >>> +#define COMPACTION_PROGRESS 3 >>> + >>> +#define compact_result_to_feedback(result) \ >>> +({ \ >>> + enum compact_result __result = result; \ >>> + (compaction_failed(__result)) ? COMPACTION_FAILED : \ >>> + (compaction_withdrawn(__result)) ? COMPACTION_WITHDRAWN : COMPACTION_PROGRESS; \ >>> +}) >> >> It seems you forgot to actually use this "function" (sorry, didn't notice >> earlier) so currently it's translating enum compact_result directly into the >> failed/withdrawn/progress strings, which is wrong. > > You are right. I've screwed while integrating the enum translation part. > >> The correct place for the result->feedback conversion should be >> TP_fast_assign, so __entry->result should become __entry->feedback. It's too >> late in TP_printk, as userspace tools (e.g. trace-cmd) won't know the >> functions that compact_result_to_feedback() uses. > > Thanks. The follow up fix should be > --- > From 82c9064698594d694b052d3847c905e90becc7c5 Mon Sep 17 00:00:00 2001 > From: Michal Hocko <mhocko@suse.com> > Date: Wed, 14 Dec 2016 19:09:10 +0100 > Subject: [PATCH] fold me "oom, trace: add compaction retry tracepoint" > > Do not forget to translate compact_result into a highlevel constants > as per Vlastimil > > Signed-off-by: Michal Hocko <mhocko@suse.com>
OK, with that:
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> --- > include/trace/events/oom.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/trace/events/oom.h b/include/trace/events/oom.h > index e9d690665b7a..38baeb27221a 100644 > --- a/include/trace/events/oom.h > +++ b/include/trace/events/oom.h > @@ -94,7 +94,7 @@ TRACE_EVENT(compact_retry, > TP_fast_assign( > __entry->order = order; > __entry->priority = priority; > - __entry->result = result; > + __entry->result = compact_result_to_feedback(result); > __entry->retries = retries; > __entry->max_retries = max_retries; > __entry->ret = ret; >
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