Re: [PATCH v3 1/3] perf diff: Support --time filter option

[Jin, Yao]

On 3/4/2019 11:41 PM, Jiri Olsa wrote:
> On Mon, Mar 04, 2019 at 08:52:38PM +0800, Jin Yao wrote:
> > For better support for perf diff, it would be useful to add --time filter
> > option to diff the samples within given time window.
> >
> > It supports time percent with multipe time ranges. Time string is
> > 'a%/n,b%/m,...' or 'a%-b%,c%-%d,...'.
> >
> > For example:
> >
> > Select the second 10% time slice to diff:
> > perf diff --time 10%/2
> >
> > Select from 0% to 10% time slice to diff:
> > perf diff --time 0%-10%
> >
> > Select the first and the second 10% time slices to diff:
> > perf diff --time 10%/1,10%/2
> >
> > Select from 0% to 10% and 30% to 40% slices to diff:
> > perf diff --time 0%-10%,30%-40%
> >
> > It also supports to analyze samples within given time window as:
> > <start>,<stop>. Times have the format seconds.microseconds. If start
> > is not given (i.e., time string is ',x.y') then analysis starts at
> > the beginning of the file. If stop time is not given (i.e, time
> > string is 'x.y,') then analysis goes to end of file. Time string is
> > 'a1.b1,c1.d1:a2.b2,c2.d2'. Use ':' to separate timestamps for different
> > perf.data files.
> >
> > For example, we get the timestamp information from perf script.
> >
> > perf script -i perf.data.old
> >    mgen 13940 [000]  3946.361400: ...
> >
> > perf script -i perf.data
> >    mgen 13940 [000]  3971.150589 ...
> >
> > perf diff --time 3946.361400,:3971.150589,
> >
> > It analyzes the perf.data.old from the timestamp 3946.361400 to
> > the end of perf.data.old and analyzes the perf.data from the
> > timestamp 3971.150589 to the end of perf.data.
> >
> >   v3:
> >   ---
> >   Don't parse the time string if --time option is not set.
> >   Refactor the code to make it simpler.
>
> it's much clearer now, thanks for doing this, some nits below

Thanks!

> SNIP
>
> > +
> >   static int __cmd_diff(void)
> >   {
> >   	struct data__file *d;
> >   	int ret = -EINVAL, i;
> > +	char *abstime_ostr, *abstime_tmp;
> > +
> > +	abstime_ostr = abstime_str_dup();
> > +	abstime_tmp = abstime_ostr;
>
> could be just one line:
>
> 	abstime_ostr = abstime_tmp = abstime_str_dup();
>
> also please fail if the allocation fails

OK, I will fix that.

> >   
> >   	data__for_each_file(i, d) {
> > -		d->session = perf_session__new(&d->data, false, &tool);
> > +		d->session = perf_session__new(&d->data, false, &pdiff.tool);
> >   		if (!d->session) {
> >   			pr_err("Failed to open %s\n", d->data.path);
> >   			ret = -1;
> >   			goto out_delete;
> >   		}
> >   
> > +		if (pdiff.time_str) {
> > +			ret = parse_time_str(d, abstime_ostr, &abstime_tmp);
> > +			if (ret < 0)
> > +				goto out_delete;
> > +		}
> > +
> >   		ret = perf_session__process_events(d->session);
> >   		if (ret) {
> >   			pr_err("Failed to process %s\n", d->data.path);
> > @@ -791,6 +889,9 @@ static int __cmd_diff(void)
> >   		}
> >   
> >   		perf_evlist__collapse_resort(d->session->evlist);
> > +
> > +		if (pdiff.ptime_range)
> > +			zfree(&pdiff.ptime_range);
> >   	}
> >   
> >   	data_process();
> > @@ -802,6 +903,13 @@ static int __cmd_diff(void)
> >   	}
> >   
> >   	free(data__files);
> > +
> > +	if (pdiff.ptime_range)
> > +		zfree(&pdiff.ptime_range);
>
> is this zfree needed? you free it in a loop for every data above

Yes, we need this zfree. Because if we read the __cmd_diff() in 
uiltin-diff.c directly (not only read from this patch), we may see other 
"goto out_delete" cases, the zfree in loop may be not called. So we need 
an additional zfree checking in error handling.

Thanks
Jin Yao

> jirka
>
>
> SNIP