linux-kernel - Re: [PATCH v2 4/7] perf diff: Use hists to manage basic blocks per symbol

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Date:   Thu, 6 Jun 2019 09:57:16 +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 4/7] perf diff: Use hists to manage basic blocks per
 symbol



On 6/5/2019 7:44 PM, Jiri Olsa wrote:
> On Mon, Jun 03, 2019 at 10:36:14PM +0800, Jin Yao wrote:
> 
> SNIP
> 
>>   		data__for_each_file_new(i, d) {
>>   			pair = get_pair_data(he, d);
>>   			if (!pair)
>> @@ -510,6 +683,9 @@ static void hists__precompute(struct hists *hists)
>>   			case COMPUTE_WEIGHTED_DIFF:
>>   				compute_wdiff(he, pair);
>>   				break;
>> +			case COMPUTE_CYCLES:
>> +				process_block_per_sym(pair, d);
>> +				break;
>>   			default:
>>   				BUG_ON(1);
>>   			}
>> @@ -713,6 +889,14 @@ hist_entry__cmp_wdiff_idx(struct perf_hpp_fmt *fmt __maybe_unused,
>>   					   sort_compute);
>>   }
>>   
>> +static int64_t
>> +hist_entry__cmp_cycles_idx(struct perf_hpp_fmt *fmt __maybe_unused,
>> +			   struct hist_entry *left __maybe_unused,
>> +			   struct hist_entry *right __maybe_unused)
>> +{
>> +	return 0;
>> +}
> 
> this is hist_entry__cmp_nop.. please use it instead and
> explain in comment why for COMPUTE_CYCLES we need the
> default sort
> 
> jirka
> 

fmt->sort should be set otherwise since fmt->sort will be called without 
checking valid, the crash happens. Yes, I should use hist_entry__cmp_nop 
instead, and will add some comments for COMPUTE_CYCLES.

Thanks
Jin Yao