linux-kernel - Re: [PATCH v3 1/6] perf header: Record first sample time and last sample time in perf file header

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Message-ID: <20171002130057.GA22359@krava>
Date:   Mon, 2 Oct 2017 15:00:57 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     "Jin, Yao" <yao.jin@...ux.intel.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v3 1/6] perf header: Record first sample time and last
 sample time in perf file header

On Mon, Oct 02, 2017 at 08:52:59PM +0800, Jin, Yao wrote:
> 
> 
> On 10/2/2017 7:50 PM, Jiri Olsa wrote:
> > On Thu, Sep 28, 2017 at 08:45:16PM +0800, Jin Yao wrote:
> > 
> > SNIP
> > 
> >> +		return ret;
> >> +
> >> +	return do_write(ff, &evlist->last_sample_time,
> >> +			sizeof(evlist->last_sample_time));
> >> +}
> >> +
> >>  static void print_hostname(struct feat_fd *ff, FILE *fp)
> >>  {
> >>  	fprintf(fp, "# hostname : %s\n", ff->ph->env.hostname);
> >> @@ -1506,6 +1520,19 @@ static void print_group_desc(struct feat_fd *ff, FILE *fp)
> >>  	}
> >>  }
> >>  
> >> +static void print_sample_time(struct feat_fd *ff, FILE *fp)
> >> +{
> >> +	struct perf_session *session;
> >> +
> >> +	session = container_of(ff->ph, struct perf_session, header);
> >> +
> >> +	fprintf(fp, "# time of first sample : %" PRIu64 "\n",
> >> +		session->evlist->first_sample_time);
> >> +
> >> +	fprintf(fp, "# time of last sample : %" PRIu64 "\n",
> >> +		session->evlist->last_sample_time);
> > 
> > this could be done in some follow up patch, but could we
> > display this in some human readable way.. 
> > 
> > # time of first sample : 218077073264620
> > # time of last sample : 218077073395488
> > 
> > jirka
> > 
> 
> Could I add the printing of duration? For example,
> 
> duration = (double)(last_sample_time - first_sample_time) / NSEC_PER_MSEC;
> fprintf(fp, "# sample duration: %10.3f (ms)\n", duration);
> 
> fprintf(fp, "# time of first sample : %" PRIu64 "\n",
>         first_sample_time);
> 
> fprintf(fp, "# time of last sample : %" PRIu64 "\n",
>         last_sample_time);

could be, but mainly please display the time same way the perf script does:

  218482.819815

jirka