Re: [PATCH v3 03/12] perf record: introduce thread local variable

From: Namhyung Kim <namhyung@kernel.org>
To: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
	Jiri Olsa <jolsa@redhat.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Andi Kleen <ak@linux.intel.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>,
	Alexander Antonov <alexander.antonov@linux.intel.com>
Subject: Re: [PATCH v3 03/12] perf record: introduce thread local variable
Date: Fri, 20 Nov 2020 19:20:21 +0900	[thread overview]
Message-ID: <20201120102021.GD94830@google.com> (raw)
In-Reply-To: <96d7752f-2c0c-330d-a11c-0961e0315c3c@linux.intel.com>

On Mon, Nov 16, 2020 at 03:16:19PM +0300, Alexey Budankov wrote:
> 
> Introduce thread local variable and use it for threaded trace streaming.
> Use thread affinity mask instead or record affinity mask in affinity modes.
> Introduce and use evlist__ctlfd_update() function to propogate external
> control commands to global evlist object.
> 
> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
> ---
>  tools/perf/builtin-record.c | 137 ++++++++++++++++++++++++------------
>  tools/perf/util/evlist.c    |  16 +++++
>  tools/perf/util/evlist.h    |   1 +
>  3 files changed, 109 insertions(+), 45 deletions(-)
> 
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 765a90e38f69..e41e1cd90168 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
[SNIP]
> @@ -2114,20 +2165,26 @@ 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;
> +
> +			if (thread->ctlfd_pos != -1) {

Isn't it only for the first thread?  I guess all thread should have
non-negative ctlfd_pos so this check seems meaningless, no?

Thanks,
Namhyung

> +				evlist__ctlfd_update(rec->evlist,
> +					&thread->pollfd.entries[thread->ctlfd_pos]);
> +			}
>  		}
>  
>  		if (evlist__ctlfd_process(rec->evlist, &cmd) > 0) {
> @@ -2175,18 +2232,20 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>  		goto out_child;
>  	}
>  
> -	if (!quiet)
> -		fprintf(stderr, "[ perf record: Woken up %ld times to write data ]\n", waking);
> -
>  	if (target__none(&rec->opts.target))
>  		record__synthesize_workload(rec, true);
>  
>  out_child:
> +	record__stop_threads(rec, &waking);
> +out_free_threads:
>  	record__free_thread_data(rec);
>  	evlist__finalize_ctlfd(rec->evlist);
>  	record__mmap_read_all(rec, true);
>  	record__aio_mmap_read_sync(rec);
>  
> +	if (!quiet)
> +		fprintf(stderr, "[ perf record: Woken up %ld times to write data ]\n", waking);
> +
>  	if (rec->session->bytes_transferred && rec->session->bytes_compressed) {
>  		ratio = (float)rec->session->bytes_transferred/(float)rec->session->bytes_compressed;
>  		session->header.env.comp_ratio = ratio + 0.5;
> @@ -2995,17 +3054,6 @@ 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_alloc(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;
> @@ -3134,7 +3182,6 @@ 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);
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 8bdf3d2c907c..758a4896fedd 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -1970,6 +1970,22 @@ int evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd)
>  	return err;
>  }
>  
> +int evlist__ctlfd_update(struct evlist *evlist, struct pollfd *update)
> +{
> +	int ctlfd_pos = evlist->ctl_fd.pos;
> +	struct pollfd *entries = evlist->core.pollfd.entries;
> +
> +	if (!evlist__ctlfd_initialized(evlist))
> +		return 0;
> +
> +	if (entries[ctlfd_pos].fd != update->fd ||
> +	    entries[ctlfd_pos].events != update->events)
> +		return -1;
> +
> +	entries[ctlfd_pos].revents = update->revents;
> +	return 0;
> +}
> +
>  struct evsel *evlist__find_evsel(struct evlist *evlist, int idx)
>  {
>  	struct evsel *evsel;
> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
> index e1a450322bc5..9b73d6ccf066 100644
> --- a/tools/perf/util/evlist.h
> +++ b/tools/perf/util/evlist.h
> @@ -380,6 +380,7 @@ void evlist__close_control(int ctl_fd, int ctl_fd_ack, bool *ctl_fd_close);
>  int evlist__initialize_ctlfd(struct evlist *evlist, int ctl_fd, int ctl_fd_ack);
>  int evlist__finalize_ctlfd(struct evlist *evlist);
>  bool evlist__ctlfd_initialized(struct evlist *evlist);
> +int evlist__ctlfd_update(struct evlist *evlist, struct pollfd *update);
>  int evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd);
>  int evlist__ctlfd_ack(struct evlist *evlist);
>  
> -- 
> 2.24.1
> 
> 