Messages in this thread | | | Date | Fri, 5 Jan 2018 09:53:41 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v7 2/6] perf record: Get the first sample time and last sample time |
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Em Fri, Jan 05, 2018 at 09:15:03AM +0800, Jin, Yao escreveu: > > > On 1/5/2018 3:09 AM, Arnaldo Carvalho de Melo wrote: > > Em Fri, Dec 08, 2017 at 09:13:42PM +0800, Jin Yao escreveu: > > > In the default 'perf record' configuration, all samples are processed, > > > to create the HEADER_BUILD_ID table. So it's very easy to get the > > > first/last samples and save the time to perf file header via the > > > function write_sample_time(). > > > > > > Later, at post processing time, perf report/script will fetch > > > the time from perf file header. > > > > So, at this point I was expecting that that record would be present on > > the perf.data file: > > > > [acme@jouet perf]$ perf record --timestamp-boundary sleep 1 > > Cannot read kernel map > > [ perf record: Woken up 1 times to write data ] > > [ perf record: Captured and wrote 0.001 MB perf.data (7 samples) ] > > [acme@jouet perf]$ perf report -D | grep PERF_RECORD_SAMPLE | wc -l > > 7 > > [acme@jouet perf]$ perf report -D | grep PERF_RECORD_SAMPLE_TIME > > [acme@jouet perf]$ > > > > What am I doing wrong? > > > > To clarify, this is with just the first two patches in this series > > applied. > > > > - Arnaldo > > Hi Arnaldo, > > The timestamp boundary information is saved in perf file header.
Right, my bad, I somehow thought it would be as PERF_RECORD_SAMPLE_TIME, duh.
Will continue reviewing, sorry about that.
- Arnaldo
> So if we want to look at them, we need to add '--header' in perf report. > > For example, > > root@skl:/tmp# perf report -D --header | grep 'time of' > # time of first sample : 248333.706656 > # time of last sample : 248357.215328 > > Thanks > Jin Yao
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