Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
IronPort-SDR: ZoOsFt/VOlVslvC7EP8bEsugmd8aV6GlyY2ejKNTCQI8CVpNe9irPfIVYLLJny4f5Rr1AdJm9h
 lwfIQgQ2T/AQ==
IronPort-SDR: t9zRy+M+jG/vIQR4eT1EhJAChy4qMB2lbHjKm6AGunEVfUsUhx0bgP5nIPJSGkcWpDEGznCpa9
 wAsTfnNeK/Aw==
Subject: Re: [PATCH v8 12/13] perf record: implement control commands handling
To:     Jiri Olsa <jolsa@redhat.com>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Andi Kleen <ak@linux.intel.com>,
        linux-kernel <linux-kernel@vger.kernel.org>
References: <0781a077-aa82-5b4a-273e-c17372a72b93@linux.intel.com>
 <f48c5f58-96ea-b1f0-a7e6-55315a292bce@linux.intel.com>
 <20200623145434.GD2619137@krava>
From:   Alexey Budankov <alexey.budankov@linux.intel.com>
Organization: Intel Corp.
Message-ID: <3107d9cd-03ec-34aa-4226-393547c55517@linux.intel.com>
Date:   Wed, 24 Jun 2020 17:00:12 +0300
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101
 Thunderbird/68.9.0
MIME-Version: 1.0
In-Reply-To: <20200623145434.GD2619137@krava>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 23.06.2020 17:54, Jiri Olsa wrote:
> On Wed, Jun 17, 2020 at 11:43:58AM +0300, Alexey Budankov wrote:
>>
>> Implement handling of 'enable' and 'disable' control commands
>> coming from control file descriptor.
>>
>> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
>> ---
>>  tools/perf/builtin-record.c | 16 ++++++++++++++++
>>  1 file changed, 16 insertions(+)
>>
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index d0b29a1070a0..0394e068dde8 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -1527,6 +1527,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>>  	bool disabled = false, draining = false;
>>  	int fd;
>>  	float ratio = 0;
>> +	enum evlist_ctl_cmd cmd = EVLIST_CTL_CMD_UNSUPPORTED;
>>  
>>  	atexit(record__sig_exit);
>>  	signal(SIGCHLD, sig_handler);
>> @@ -1830,6 +1831,21 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>>  				alarm(rec->switch_output.time);
>>  		}
>>  
>> +		if (evlist__ctlfd_process(rec->evlist, &cmd) > 0) {
>> +			switch (cmd) {
>> +			case EVLIST_CTL_CMD_ENABLE:
>> +				pr_info(EVLIST_ENABLED_MSG);
>> +				break;
>> +			case EVLIST_CTL_CMD_DISABLE:
>> +				pr_info(EVLIST_DISABLED_MSG);
>> +				break;
>> +			case EVLIST_CTL_CMD_ACK:
>> +			case EVLIST_CTL_CMD_UNSUPPORTED:
>> +			default:
>> +				break;
>> +			}
>> +		}
> 
> so there's still the filter call like:
> 
>                         if (evlist__filter_pollfd(rec->evlist, POLLERR | POLLHUP) == 0)
>                                 draining = true;
> 
> it will never be 0 if the control fds are stil alive no?

Due to change in filter_pollfd() and preceding evlist__ctlfd_process() call
now control fd is not counted by filter_pollfd().

However event fds with .revents == 0 are not counted either and this breaks
the algorithm thus something more is still required to cover this gap.

~Alexey

> 
> jirka
>