Messages in this thread | | | Date | Thu, 7 May 2015 11:21:20 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH V8 7/8] perf, x86: introduce PERF_RECORD_LOST_SAMPLES |
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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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