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

From: Jin, Yao
Date: Wed Dec 11 2019 - 07:36:31 EST




On 12/11/2019 8:14 PM, Jiri Olsa wrote:
On Wed, Dec 11, 2019 at 08:01:44PM +0800, Jin, Yao wrote:


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. :)

aah, I missed it's actualy == used in the first one ;-)

why don't you just call it directly?

ret = field_cmp(fields_a[idx], fields_b[idx])
if (ret)
goto out;

jirka


Oh, yes, we can use simpler code. For example,

if (idx >= 1 && idx < nr_members) {
ret = field_cmp(fields_a[idx], fields_b[idx]);
if (ret)
goto out;
}

Thanks
Jin Yao