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