linux/tools/perf/util/tool.h
Kan Liang c4937a91ea perf tools: handle PERF_RECORD_LOST_SAMPLES
This patch modifies the perf tool to handle the new RECORD type,
PERF_RECORD_LOST_SAMPLES.

The number of lost-sample events is stored in
.nr_events[PERF_RECORD_LOST_SAMPLES]. The exact number of samples
which the kernel dropped is stored in total_lost_samples.

When the percentage of dropped samples is greater than 5%, a warning
is printed.

Here are some examples:

Eg 1, Recording different frequently-occurring events is safe with the
      patch. Only a very low drop rate is associated with such actions.

$ perf record -e '{cycles:p,instructions:p}' -c 20003 --no-time ~/tchain ~/tchain

$ perf report -D | tail
          SAMPLE events:     120243
           MMAP2 events:          5
    LOST_SAMPLES events:         24
  FINISHED_ROUND events:         15
cycles:p stats:
           TOTAL events:      59348
          SAMPLE events:      59348
instructions:p stats:
           TOTAL events:      60895
          SAMPLE events:      60895

$ perf report --stdio --group
 # To display the perf.data header info, please use --header/--header-only options.
 #
 #
 # Total Lost Samples: 24
 #
 # Samples: 120K of event 'anon group { cycles:p, instructions:p }'
 # Event count (approx.): 24048600000
 #
 #         Overhead  Command      Shared Object     Symbol
 # ................  ...........  ................
 ..................................
 #
    99.74%  99.86%  tchain_edit  tchain_edit       [.] f3
     0.09%   0.02%  tchain_edit  tchain_edit       [.] f2
     0.04%   0.00%  tchain_edit  [kernel.vmlinux]  [k] ixgbe_read_reg

Eg 2, Recording the same thing multiple times can lead to high drop
      rate, but it is not a useful configuration.

$ perf record -e '{cycles:p,cycles:p}' -c 20003 --no-time ~/tchain
Warning: Processed 600592 samples and lost 99.73% samples!
[perf record: Woken up 148 times to write data]
[perf record: Captured and wrote 36.922 MB perf.data (1206322 samples)]
[perf record: Woken up 1 times to write data]
[perf record: Captured and wrote 0.121 MB perf.data (1629 samples)]

Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@infradead.org
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/1431285195-14269-9-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-07 16:09:06 +02:00

64 lines
1.4 KiB
C

#ifndef __PERF_TOOL_H
#define __PERF_TOOL_H
#include <stdbool.h>
#include <linux/types.h>
struct perf_session;
union perf_event;
struct perf_evlist;
struct perf_evsel;
struct perf_sample;
struct perf_tool;
struct machine;
struct ordered_events;
typedef int (*event_sample)(struct perf_tool *tool, union perf_event *event,
struct perf_sample *sample,
struct perf_evsel *evsel, struct machine *machine);
typedef int (*event_op)(struct perf_tool *tool, union perf_event *event,
struct perf_sample *sample, struct machine *machine);
typedef int (*event_attr_op)(struct perf_tool *tool,
union perf_event *event,
struct perf_evlist **pevlist);
typedef int (*event_op2)(struct perf_tool *tool, union perf_event *event,
struct perf_session *session);
typedef int (*event_oe)(struct perf_tool *tool, union perf_event *event,
struct ordered_events *oe);
typedef s64 (*event_op3)(struct perf_tool *tool, union perf_event *event,
struct perf_session *session);
struct perf_tool {
event_sample sample,
read;
event_op mmap,
mmap2,
comm,
fork,
exit,
lost,
lost_samples,
aux,
itrace_start,
throttle,
unthrottle;
event_attr_op attr;
event_op2 tracing_data;
event_oe finished_round;
event_op2 build_id,
id_index,
auxtrace_info,
auxtrace_error;
event_op3 auxtrace;
bool ordered_events;
bool ordering_requires_timestamps;
};
#endif /* __PERF_TOOL_H */