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Date: Fri, 26 Feb 2021 08:41:26 +0800
From: "Jin, Yao" <yao.jin@...ux.intel.com>
To: Jiri Olsa <jolsa@...hat.com>
Cc: kernel test robot <oliver.sang@...el.com>,
Chris Wilson <chris@...is-wilson.co.uk>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...nel.org>,
Tvrtko Ursulin <tvrtko.ursulin@...el.com>,
Matthew Brost <matthew.brost@...el.com>,
LKML <linux-kernel@...r.kernel.org>, lkp@...ts.01.org,
lkp@...el.com, Andi Kleen <ak@...ux.intel.com>,
Adrian Hunter <adrian.hunter@...el.com>,
"Liang, Kan" <kan.liang@...el.com>, "Jin, Yao" <yao.jin@...el.com>,
"Yi, Ammy" <ammy.yi@...el.com>
Subject: Re: [drm/i915/gt] 8c3b1ba0e7:
perf-sanity-tests.Parse_event_definition_strings.fail
Hi Jiri,
On 2/26/2021 3:03 AM, Jiri Olsa wrote:
> On Thu, Feb 25, 2021 at 07:50:46PM +0100, Jiri Olsa wrote:
>> On Thu, Feb 25, 2021 at 07:16:44PM +0100, Jiri Olsa wrote:
>>> On Thu, Feb 25, 2021 at 02:33:57PM +0100, Jiri Olsa wrote:
>>>> On Thu, Feb 25, 2021 at 04:06:23PM +0800, Jin, Yao wrote:
>>>>> Hi Chris, Arnaldo, Jiri,
>>>>>
>>>>> We observe the parsing error for "software/xxx/" on some platforms.
>>>>>
>>>>> For example,
>>>>>
>>>>> # perf stat -e software/r1a/ -a -- sleep 1
>>>>> event syntax error: 'software/r1a/'
>>>>> \___ parser error
>>>>> Run 'perf list' for a list of valid events
>>>>>
>>>>> Usage: perf stat [<options>] [<command>]
>>>>>
>>>>> -e, --event <event> event selector. use 'perf list' to list available events
>>>>>
>>>>> And perf test is failed too.
>>>>>
>>>>> # perf test 6 -vv
>>>>> ...
>>>>> running test 4 'software/r1a/'failed to parse event 'software/r1a/', err 1, str 'parser error'
>>>>> event syntax error: 'software/r1a/'
>>>>> \___ parser error
>>>>>
>>>>> running test 4 'software/r0x1a/'failed to parse event 'software/r0x1a/', err 1, str 'parser error'
>>>>> event syntax error: 'software/r0x1a/'
>>>>> \___ parser error
>>>>> ...
>>>>>
>>>>> The issue should be the conflict between event "i915/software-gt-awake-time/" and pmu "software".
>>>>>
>>>>> # perf list | grep i915/software
>>>>> i915/software-gt-awake-time/ [Kernel PMU event]
>>>>>
>>>>> Perf supports the event format as "prefix-xxx-suffix", so the "software"
>>>>> string in "software-gt-awake-time" is added to perf_pmu_events_list as
>>>>> PMU_EVENT_SYMBOL_PREFIX. When parsing the string such as "software/xxx/",
>>>>> it’s parsed as PMU_EVENT_SYMBOL_PREFIX for "software", then it would error
>>>>> out in next processing.
>>>>>
>>>>> So the easy way is to rename "software-gt-awake-time" to "gt-awake-time",
>>>>> right? Otherwise we have to hardcode something in perf tool.
>>>>>
>>>>> What do you think of this issue and the solution?
>>>>>
>>>>> BTW, as the robot reported, it's related to the commit 8c3b1ba0e7ea
>>>>> ("drm/i915/gt: Track the overall awake/busy time").
>>>>
>>>> yes, I think you're right.. I'll try to reproduce and check on this
>>>>
>>>> I'm still not clear why is that parsing fail if those 2 events are
>>>> distinguished by - and / ... but yep, we are asking for trouble in
>>>> here ;-)
>>>>
>>>> I think we could either prioritaze one or add extra check when we
>>>> add prefix-xxx-suffix events and do not add ones that have conflict..
>>>> that seems like best solution to me now
>>>
>>> would patch below work for you?
>>>
>>> jirka
>>
>> and now with more fixes after I ran tests ;-)
>>
>> we should perhaps add also same check for non '-' aliases, I'll check
>
> and one more version ;-)
>
> jirka
>
>
> ---
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index 42c84adeb2fb..d9e795056d15 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -2028,30 +2028,49 @@ static void perf_pmu__parse_init(void)
> perf_pmu_events_list_num = -1;
> return;
> }
> - perf_pmu_events_list = malloc(sizeof(struct perf_pmu_event_symbol) * len);
> + perf_pmu_events_list = zalloc(sizeof(struct perf_pmu_event_symbol) * len);
> if (!perf_pmu_events_list)
> return;
> - perf_pmu_events_list_num = len;
>
> len = 0;
> pmu = NULL;
> while ((pmu = perf_pmu__scan(pmu)) != NULL) {
> list_for_each_entry(alias, &pmu->aliases, list) {
> struct perf_pmu_event_symbol *p = perf_pmu_events_list + len;
> - char *tmp = strchr(alias->name, '-');
> + char *prefix = strdup(alias->name);
> + char *tmp = strchr(prefix, '-');
> +
> + if (tmp != NULL)
> + *tmp = 0;
> +
> + /*
> + * Skip any prefix that conflicts with pmu name,
> + * otherwise the event parser gets confused.
> + */
> + if (perf_pmu__find(prefix)) {
> + pr_debug2("perf_pmu__parse_init: skipping conflicting alias '%s'\n",
> + alias->name);
> + free(prefix);
> + continue;
> + }
>
> if (tmp != NULL) {
> - SET_SYMBOL(strndup(alias->name, tmp - alias->name),
> - PMU_EVENT_SYMBOL_PREFIX);
> + SET_SYMBOL(prefix, PMU_EVENT_SYMBOL_PREFIX);
> p++;
> SET_SYMBOL(strdup(++tmp), PMU_EVENT_SYMBOL_SUFFIX);
> len += 2;
> } else {
> - SET_SYMBOL(strdup(alias->name), PMU_EVENT_SYMBOL);
> + SET_SYMBOL(prefix, PMU_EVENT_SYMBOL);
> len++;
> }
> }
> }
> +
> + /* unlikely, but still.. */
> + if (!len)
> + goto err;
> + perf_pmu_events_list_num = len;
> +
> qsort(perf_pmu_events_list, len,
> sizeof(struct perf_pmu_event_symbol), comp_pmu);
>
>
Thanks so much for the patch! It works with my tests.
# ./perf test 6
6: Parse event definition strings : Ok
# ./perf stat -e software/r1a/ -a -- sleep 1
Performance counter stats for 'system wide':
<not supported> software/r1a/
1.000940433 seconds time elapsed
In theory, do we also need to check suffix as well? I think returning PMU_EVENT_SYMBOL_SUFFIX may
also confuse the parser. But yes, we don't have this case now.
Thanks
Jin Yao
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