Messages in this thread | | | Date | Wed, 3 Aug 2011 18:28:59 +0800 | From | Han Pingtian <> | Subject | perf complains losting events |
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Hi,
I find there is a comment about losting events:
/* * The kernel collects the number of events it couldn't send in a stretch and * when possible sends this number in a PERF_RECORD_LOST event. The number of * such "chunks" of lost events is stored in .nr_events[PERF_EVENT_LOST] while * total_lost tells exactly how many events the kernel in fact lost, i.e. it is * the sum of all struct lost_event.lost fields reported. * * The total_period is needed because by default auto-freq is used, so * multipling nr_events[PERF_EVENT_SAMPLE] by a frequency isn't possible to get * the total number of low level events, it is necessary to to sum all struct * sample_event.period and stash the result in total_period. */
So my question is, whether the losting of events is a problem? I have saw it many times:
[root@hp-dl580g7-01 perf]# ./perf kmem record sleep 1 [ perf record: Woken up 0 times to write data ] [ perf record: Captured and wrote 21.789 MB perf.data (~951977 samples) ] Processed 0 events and LOST 76148!
Check IO/CPU overload!
[root@hp-dl580g7-01 perf]# ./perf kmem stat Processed 0 events and LOST 76148!
Check IO/CPU overload!
SUMMARY ======= Total bytes requested: 5725028 Total bytes allocated: 6291512 Total bytes wasted on internal fragmentation: 566484 Internal fragmentation: 9.003941% Cross CPU allocations: 28/84295
-- Han Pingtian Quality Engineer hpt @ #kernel-qe Red Hat, Inc Freedom ... courage ... Commitment ... ACCOUNTABILITY
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