Re: [PATCH v2 2/6] perf test: Handle metric reuse in pmu-events parsing test

John Garry
2021-04-06T11:03:05Z

On 01/04/2021 14:49, Jiri Olsa wrote:
> On Thu, Mar 25, 2021 at 06:33:14PM +0800, John Garry wrote:
>
> SNIP
>
>> +struct metric {
>> + struct list_head list;
>> + struct metric_ref metric_ref;
>> +};
>> +
>> +static int resolve_metric_simple(struct expr_parse_ctx *pctx,
>> + struct list_head *compound_list,
>> + struct pmu_events_map *map,
>> + const char *metric_name)
>> +{
>> + struct hashmap_entry *cur, *cur_tmp;
>> + struct metric *metric, *tmp;
>> + size_t bkt;
>> + bool all;
>> + int rc;
>> +
>> + do {
>> + all = true;
>> + hashmap__for_each_entry_safe((&pctx->ids), cur, cur_tmp, bkt) {
>> + struct metric_ref *ref;
>> + struct pmu_event *pe;
>> +
>> + pe = metrcgroup_find_metric(cur->key, map);

*

>> + if (!pe)
>> + continue;
>> +
>> + if (!strcmp(metric_name, (char *)cur->key)) {
>> + pr_warning("Recursion detected for metric %s\n", metric_name);
>> + rc = -1;
>> + goto out_err;
>> + }
>> +
>> + all = false;
>> +
>> + /* The metric key itself needs to go out.. */
>> + expr__del_id(pctx, cur->key);
>> +
>> + metric = malloc(sizeof(*metric));
>> + if (!metric) {
>> + rc = -ENOMEM;
>> + goto out_err;
>> + }
>> +
>> + ref = &metric->metric_ref;
>> + ref->metric_name = pe->metric_name;
>> + ref->metric_expr = pe->metric_expr;
>> + list_add_tail(&metric->list, compound_list);
>> +
>> + rc = expr__find_other(pe->metric_expr, NULL, pctx, 0);
>

Hi Jirka,

> so this might add new items to pctx->ids, I think you need
> to restart the iteration as we do it in __resolve_metric
> otherwise you could miss some new keys

I thought that I was doing this. Indeed, this code is very much like
__resolve_metric() ;)

So expr__find_other() may add a new item to pctx->ids, and we always
iterate again, and try to lookup any pmu_events, *, above. If none
exist, then we have broken down pctx into primitive events aliases and
unresolvable metrics, and stop iterating. And then unresolvable metrics
would be found in check_parse_cpu().

As an example, we can deal with metric test1, below, which references 2x
other metrics:

{
"MetricExpr": "IDQ_UOPS_NOT_DELIVERED.CORE / (4 * (( (
CPU_CLK_UNHALTED.THREAD / 2 ) * ( 1 + CPU_CLK_UNHALTED.ONE_THREAD_ACTIVE
/ CPU_CLK_UNHALTED.REF_XCLK ) )))",
"MetricName": "Frontend_Bound",
},
{
"MetricExpr": "( UOPS_ISSUED.ANY - UOPS_RETIRED.RETIRE_SLOTS +
4 * INT_MISC.RECOVERY_CYCLES ) / (4 * cycles)",
"MetricName": "Bad_Speculation",
},
{
"MetricExpr": "Bad_Speculation + Frontend_Bound",
"MetricName": "test1",
},

Does that satisfy your concern, or have I missed something?

Thanks,
John

>
> jirka
>
>> + if (rc)
>> + goto out_err;
>> + }
>> + } while (!all);
>> +
>> + return 0;
>> +
>> +out_err:
>> + list_for_each_entry_safe(metric, tmp, compound_list, list)
>> + free(metric);
>> +
>> + return rc;
>> +
>> +}
>
> SNIP
>
> .
>