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Date: Fri, 3 Mar 2017 14:27:09 +0530
From: Hari Bathini <hbathini@...ux.vnet.ibm.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: ast@...com, peterz@...radead.org,
lkml <linux-kernel@...r.kernel.org>,
alexander.shishkin@...ux.intel.com, mingo@...hat.com,
daniel@...earbox.net, rostedt@...dmis.org,
Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
ebiederm@...ssion.com, sargun@...gun.me,
Aravinda Prasad <aravinda@...ux.vnet.ibm.com>,
brendan.d.gregg@...il.com, jolsa@...hat.com
Subject: Re: [PATCH v7 4/8] perf tool: synthesize namespace events for current
processes
On Thursday 02 March 2017 02:35 AM, Arnaldo Carvalho de Melo wrote:
> Em Tue, Feb 21, 2017 at 07:31:44PM +0530, Hari Bathini escreveu:
>> Synthesize PERF_RECORD_NAMESPACES events for processes that were
>> running prior to invocation of perf record, the data for which is
>> taken from /proc/$PID/ns. These changes make way for analyzing
>> events with regard to namespaces.
>>
>> Signed-off-by: Hari Bathini <hbathini@...ux.vnet.ibm.com>
>> ---
>> tools/perf/builtin-record.c | 27 +++++++++--
>> tools/perf/util/event.c | 107 +++++++++++++++++++++++++++++++++++++++++--
>> tools/perf/util/event.h | 6 ++
>> 3 files changed, 130 insertions(+), 10 deletions(-)
>>
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index a8b9a78..f4bf6a6 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -986,6 +986,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>> */
>> if (forks) {
>> union perf_event *event;
>> + pid_t tgid;
>>
>> event = malloc(sizeof(event->comm) + machine->id_hdr_size);
>> if (event == NULL) {
>> @@ -999,10 +1000,28 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>> * cannot see a correct process name for those events.
>> * Synthesize COMM event to prevent it.
>> */
>> - perf_event__synthesize_comm(tool, event,
>> - rec->evlist->workload.pid,
>> - process_synthesized_event,
>> - machine);
>> + tgid = perf_event__synthesize_comm(tool, event,
>> + rec->evlist->workload.pid,
>> + process_synthesized_event,
>> + machine);
>> + free(event);
>> +
>> + if (tgid == -1)
>> + goto out_child;
>> +
>> + event = malloc(sizeof(event->namespaces) + machine->id_hdr_size);
>> + if (event == NULL) {
>> + err = -ENOMEM;
>> + goto out_child;
>> + }
>> +
>> + /*
>> + * Synthesize NAMESPACES event for the command specified.
>> + */
>> + perf_event__synthesize_namespaces(tool, event,
>> + rec->evlist->workload.pid,
>> + tgid, process_synthesized_event,
>> + machine);
>> free(event);
>>
>> perf_evlist__start_workload(rec->evlist);
>> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
>> index f118eac..c8c112a 100644
>> --- a/tools/perf/util/event.c
>> +++ b/tools/perf/util/event.c
>> @@ -50,6 +50,16 @@ static const char *perf_event__names[] = {
>> [PERF_RECORD_TIME_CONV] = "TIME_CONV",
>> };
>>
>> +static const char *perf_ns__names[] = {
>> + [NET_NS_INDEX] = "net",
>> + [UTS_NS_INDEX] = "uts",
>> + [IPC_NS_INDEX] = "ipc",
>> + [PID_NS_INDEX] = "pid",
>> + [USER_NS_INDEX] = "user",
>> + [MNT_NS_INDEX] = "mnt",
>> + [CGROUP_NS_INDEX] = "cgroup",
>> +};
>> +
>> const char *perf_event__name(unsigned int id)
>> {
>> if (id >= ARRAY_SIZE(perf_event__names))
>> @@ -59,6 +69,13 @@ const char *perf_event__name(unsigned int id)
>> return perf_event__names[id];
>> }
>>
>> +static const char *perf_ns__name(unsigned int id)
>> +{
>> + if (id >= ARRAY_SIZE(perf_ns__names))
>> + return "UNKNOWN";
>> + return perf_ns__names[id];
>> +}
>> +
>> static int perf_tool__process_synth_event(struct perf_tool *tool,
>> union perf_event *event,
>> struct machine *machine,
>> @@ -204,6 +221,56 @@ pid_t perf_event__synthesize_comm(struct perf_tool *tool,
>> return tgid;
>> }
>>
>> +static void perf_event__get_ns_link_info(pid_t pid, const char *ns,
>> + struct perf_ns_link_info *ns_link_info)
>> +{
>> + struct stat64 st;
>> + char proc_ns[128];
>> +
>> + sprintf(proc_ns, "/proc/%u/ns/%s", pid, ns);
>> + if (stat64(proc_ns, &st) == 0) {
>> + ns_link_info->dev = st.st_dev;
>> + ns_link_info->ino = st.st_ino;
>> + }
>> +}
>> +
>> +int perf_event__synthesize_namespaces(struct perf_tool *tool,
>> + union perf_event *event,
>> + pid_t pid, pid_t tgid,
>> + perf_event__handler_t process,
>> + struct machine *machine)
>> +{
>> + u32 idx;
>> + struct perf_ns_link_info *ns_link_info;
>> +
>> + if (!tool->namespace_events)
>> + return 0;
>> +
>> + memset(&event->namespaces, 0,
>> + sizeof(event->namespaces) + machine->id_hdr_size);
>> +
>> + event->namespaces.pid = tgid;
>> + event->namespaces.tid = pid;
>> +
>> + event->namespaces.nr_namespaces = NR_NAMESPACES;
> Huh? Don't you have to first figure out how many namespaces a process is
> in to then set this field?
>
NR_NAMESPACES is the total number of namespaces. For synthesized namespace
events, data is obtained from /proc/<pid>/ns/ dir. Looking at this dir, it
is difficult to arrive at the total number of namespaces in kernel, as
some namespaces can be compiled in/out of the kernel. NR_NAMESPACES is
used instead. Its value is most likely the same for kernel and perf tool
unless a new namespace is introduced - the warning in previous patch is
intended to alert the user about such scenario.
Thanks
Hari
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