linux-kernel - Re: [PATCH v2 1/3] perf report: Change sort order by a specified event in group

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Message-ID: <6ba174a8-309e-9410-e6ea-ac7bb7187757@linux.intel.com>
Date:   Wed, 11 Dec 2019 20:01:44 +0800
From:   "Jin, Yao" <yao.jin@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.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 v2 1/3] perf report: Change sort order by a specified
 event in group



On 12/11/2019 7:38 PM, Jiri Olsa wrote:
> On Wed, Dec 11, 2019 at 03:30:34PM +0800, Jin Yao wrote:
> 
> SNIP
> 
>> +
>> +static int __hpp__group_sort_idx(struct hist_entry *a, struct hist_entry *b,
>> +				 hpp_field_fn get_field, int idx)
>> +{
>> +	struct evsel *evsel = hists_to_evsel(a->hists);
>> +	u64 *fields_a, *fields_b;
>> +	int cmp, nr_members, ret, i;
>> +
>> +	cmp = field_cmp(get_field(a), get_field(b));
>> +	if (!perf_evsel__is_group_event(evsel))
>> +		return cmp;
>> +
>> +	nr_members = evsel->core.nr_members;
>> +	ret = pair_fields_alloc(a, b, get_field, nr_members,
>> +			      &fields_a, &fields_b);
>> +	if (ret) {
>> +		ret = cmp;
>> +		goto out;
>> +	}
>> +
>> +	for (i = 1; i < nr_members; i++) {
>> +		if (i == idx) {
>> +			ret = field_cmp(fields_a[i], fields_b[i]);
>> +			if (ret)
>> +				goto out;
>> +		}
>> +	}
>> +
>> +	if (cmp) {
>> +		ret = cmp;
>> +		goto out;
>> +	}
>> +
>> +	for (i = 1; i < nr_members; i++) {
>> +		if (i != idx) {
>> +			ret = field_cmp(fields_a[i], fields_b[i]);
>> +			if (ret)
>> +				goto out;
>> +		}
> 
> hi,
> I'm missing why we compare the fields for 2nd time in here
> 
> thanks,
> jirka
> 

Hi,

I think we may continue comparing the remaining of fields if the index 
field is equal. :)

Thanks
Jin Yao