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SubjectRe: [PATCH 12/20] perf tools: Add ->sort() member to struct sort_entry
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On Thu, 15 May 2014 15:43:10 +0200, Jiri Olsa wrote:
> On Mon, May 12, 2014 at 03:28:45PM +0900, Namhyung Kim wrote:
>
> SNIP
>
>> +static int64_t
>> +sort__sym_sort(struct hist_entry *left, struct hist_entry *right)
>> +{
>> + if (!left->ms.sym || !right->ms.sym)
>> + return cmp_null(left->ms.sym, right->ms.sym);
>> +
>> + return strcmp(right->ms.sym->name, left->ms.sym->name);
>> +}
>
> why do we need just string comparison for sort?

Because we want to sort them in alphabetical order.

>
>> +
>> static int _hist_entry__sym_snprintf(struct map *map, struct symbol *sym,
>> u64 ip, char level, char *bf, size_t size,
>> unsigned int width)
>> @@ -255,6 +271,7 @@ static int hist_entry__sym_snprintf(struct hist_entry *he, char *bf,
>> struct sort_entry sort_sym = {
>> .se_header = "Symbol",
>> .se_cmp = sort__sym_cmp,
>> + .se_sort = sort__sym_sort,
>> .se_snprintf = hist_entry__sym_snprintf,
>> .se_width_idx = HISTC_SYMBOL,
>
> so when we insert entries into hists we use se_cmp to group them
> via hist_entry__cmp
>
> the we sort this hists based on output and use se_sort to group
> them via __hists__insert_output_entry
>
> why can't we use just cmp?

As I said, the output should be sorted by symbol name. IOW, in order to
group entries in input stage, putting them into a correct group is
important, but for output stage, the order is also important.

Thanks,
Namhyung


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