Em Thu, May 07, 2015 at 11:15:20AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Thu, May 07, 2015 at 01:54:46PM +0200, Peter Zijlstra escreveu:
> > On Thu, May 07, 2015 at 01:35:24PM +0200, Peter Zijlstra wrote:
> > >
> > > - dropped the @id field from the record, it is already included in the
> > > @sample_id values.
> >
> > Hmm, this would force people to use sample_id; which in general is a
> > good idea, but should we really force that on people?
>
> Well, if there are more than one sample, we need it, right? If there is
> just one, we don't need it, what is different? Am I needing (even more)
> coffee?
>
> /me goes read some code...
I.e.:
[acme@ssdandy linux]$ perf record -e cycles usleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.013 MB perf.data (8 samples) ]
[acme@ssdandy linux]$
[acme@ssdandy linux]$ perf evlist -v
cycles: size: 112, { sample_period, sample_freq }: 4000,
sample_type: IP|TID|TIME|PERIOD, disabled: 1, inherit: 1, mmap: 1,
comm: 1, freq: 1, enable_on_exec: 1, task: 1, sample_id_all: 1,
exclude_guest: 1, mmap2: 1, comm_exec: 1
[acme@ssdandy linux]$
Just one event, no need for PERF_SAMPLE_ID.
But with > 1 events:
[acme@ssdandy linux]$ perf record -e cycles,instructions usleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.014 MB perf.data (8 samples) ]
[acme@ssdandy linux]$ perf evlist -v
cycles: size: 112, { sample_period, sample_freq }: 4000,
sample_type: IP|TID|TIME|ID|PERIOD, read_format: ID, disabled: 1,
inherit: 1, mmap: 1, comm: 1, freq: 1, enable_on_exec: 1, task: 1,
sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1
instructions: size: 112, config: 1,
{ sample_period, sample_freq }: 4000,
sample_type: IP|TID|TIME|ID|PERIOD, read_format: ID, disabled: 1,
inherit: 1, freq: 1, enable_on_exec: 1, sample_id_all: 1,
exclude_guest: 1
[acme@ssdandy linux]$
- Arnaldo
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