Re: [PATCH v12 05/16] perf record: Introduce thread local variable

Bayduraev, Alexey V
2021-12-20T09:49:33Z

On 05.12.2021 18:14, Jiri Olsa wrote:
> On Tue, Nov 23, 2021 at 05:08:01PM +0300, Alexey Bayduraev wrote:
>
> SNIP
>
>>
>> + if (record__start_threads(rec))
>> + goto out_free_threads;
>> +
>> /*
>> * When perf is starting the traced process, all the events
>> * (apart from group members) have enable_on_exec=1 set,
>> @@ -2122,7 +2175,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>> trigger_ready(&switch_output_trigger);
>> perf_hooks__invoke_record_start();
>> for (;;) {
>> - unsigned long long hits = rec->samples;
>> + unsigned long long hits = thread->samples;
>>
>> /*
>> * rec->evlist->bkw_mmap_state is possible to be
>> @@ -2176,8 +2229,8 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>>
>> if (!quiet)
>> fprintf(stderr, "[ perf record: dump data: Woken up %ld times ]\n",
>> - waking);
>> - waking = 0;
>> + record__waking(rec));
>> + thread->waking = 0;
>> fd = record__switch_output(rec, false);
>> if (fd < 0) {
>> pr_err("Failed to switch to new file\n");
>> @@ -2191,20 +2244,24 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>> alarm(rec->switch_output.time);
>> }
>>
>> - if (hits == rec->samples) {
>> + if (hits == thread->samples) {
>> if (done || draining)
>> break;
>> - err = evlist__poll(rec->evlist, -1);
>> + err = fdarray__poll(&thread->pollfd, -1);
>> /*
>> * Propagate error, only if there's any. Ignore positive
>> * number of returned events and interrupt error.
>> */
>> if (err > 0 || (err < 0 && errno == EINTR))
>> err = 0;
>> - waking++;
>> + thread->waking++;
>>
>> - if (evlist__filter_pollfd(rec->evlist, POLLERR | POLLHUP) == 0)
>> + if (fdarray__filter(&thread->pollfd, POLLERR | POLLHUP,
>> + record__thread_munmap_filtered, NULL) == 0)
>> draining = true;
>> +
>> + evlist__ctlfd_update(rec->evlist,
>> + &thread->pollfd.entries[thread->ctlfd_pos]);
>
> hm, why is this needed? we only switch to record_thread data, right?
> there should not be any processing change

Hi,

This is necessary to propagate ctlfd events from thread->pollfd to rec->evlist
to enable evlist__ctlfd_*() functionality, see [PATCH v12 04/16].
I will add explanations to the description of the patch.

Regards,
Alexey

>
> jirka
>
>> }
>>
>> if (evlist__ctlfd_process(rec->evlist, &cmd) > 0) {
>> @@ -2258,15 +2315,18 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>> }
>>
>> if (!quiet)
>> - fprintf(stderr, "[ perf record: Woken up %ld times to write data ]\n", waking);
>> + fprintf(stderr, "[ perf record: Woken up %ld times to write data ]\n",
>> + record__waking(rec));
>>
>> if (target__none(&rec->opts.target))
>> record__synthesize_workload(rec, true);
>>
>> out_child:
>> - evlist__finalize_ctlfd(rec->evlist);
>> + record__stop_threads(rec);
>> record__mmap_read_all(rec, true);
>> +out_free_threads:
>> record__free_thread_data(rec);
>> + evlist__finalize_ctlfd(rec->evlist);
>> record__aio_mmap_read_sync(rec);
>>
>> if (rec->session->bytes_transferred && rec->session->bytes_compressed) {
>> @@ -3158,17 +3218,6 @@ int cmd_record(int argc, const char **argv)
>>
>> symbol__init(NULL);
>>
>> - if (rec->opts.affinity != PERF_AFFINITY_SYS) {
>> - rec->affinity_mask.nbits = cpu__max_cpu();
>> - rec->affinity_mask.bits = bitmap_zalloc(rec->affinity_mask.nbits);
>> - if (!rec->affinity_mask.bits) {
>> - pr_err("Failed to allocate thread mask for %zd cpus\n", rec->affinity_mask.nbits);
>> - err = -ENOMEM;
>> - goto out_opts;
>> - }
>> - pr_debug2("thread mask[%zd]: empty\n", rec->affinity_mask.nbits);
>> - }
>> -
>> err = record__auxtrace_init(rec);
>> if (err)
>> goto out;
>> @@ -3313,7 +3362,6 @@ int cmd_record(int argc, const char **argv)
>>
>> err = __cmd_record(&record, argc, argv);
>> out:
>> - bitmap_free(rec->affinity_mask.bits);
>> evlist__delete(rec->evlist);
>> symbol__exit();
>> auxtrace_record__free(rec->itr);
>> --
>> 2.19.0
>>
>