So basically, in the end I think it should be possible to have the
following behavior:
perf record -a -e cycles sleep 1
perf report stat # Reports as if we ran: 'perf stat -a -e
cycles sleep 1'
perf report # Reports the usual histogram
perf report --stat # Reports the perf stat output and the
histogram
or so.
i.e. a perf.data file would by default always carry enough information
to enable the extraction of the 'perf stat' data.
At that point visualizing it is purely report-time logic, it does not
need any record-time options.
This would work for multi-event sampling as well, if we do:
perf record -a -e cycles -e branches sleep 1
then 'perf report stat' would output the same as:
$ perf stat -e cycles -e branches -a sleep 1
Performance counter stats for 'system wide':
34,174,518 cycles [100.00%]
3,155,677 branches
1.000802852 seconds time elapsed
Another neat feature this kind of workflo enables is the integration
of --repeat to perf record, so something like:
perf record --repeat 3 -a -e cycles -e branches sleep 1
would save 3 samples after each other, and would allow extraction of
the statistical stability of the measurement, and 'perf report stat'
would print the same result as a raw perf stat run would:
$ perf stat --repeat 3 -e cycles -e branches -e instructions -a sleep 1
Performance counter stats for 'system wide' (3 runs):
28,975,150,642 cycles ( +- 0.43% ) [100.00%]
10,740,235,371 branches
( +- 0.47% ) [100.00%]
44,535,464,754 instructions # 1.54 insns per cycle
( +- 0.47% )
1.005718027 seconds time elapsed
( +- 0.43% )
Or something like that. At that point we share reporting between perf
stat and perf report, no special ad-hoc options are needed to just
measure and report timestamps, it would all be a 'natural' side effect
of having perf stat.
What do you think?
Thanks,
Ingo
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