Hello everyone,
We changed the patch code a bit to include all of the VTIDs of a task
nested deep down in an arbitrary level of pid namespace.
For example, if a task is running inside a container nested in another
container, our patch will display the TID of the task from the point of
view of :
1. The root container (or the host)
2. The parent container
3. The container the task is running into
We also rebased on master, and everything is running smooth and fine on
our test machine (linux 3.19.3).
It should support down to linux 3.8.1.
Here is an example of a field:
sched_process_fork: { cpu_id = 0 }, { parent_comm = "bash", parent_tid =
10739, parent_pid = 10739, parent_ns_inum = 4026532365, child_comm =
"bash", child_tid = 10968, _vtids_length = 3, vtids = [ [0] = 10968, [1]
= 2658, [2] = 1265 ], child_pid = 10968, child_ns_inum = 4026532365 }
Any comments are greatly appreciated!
Sebastien & Francis.
On 03/31/15 11:50, Sébastien Lorrain wrote:
Hello fellow LTTNG devs,
We are students from Polytechnique Montreal and we are currently
working on an TraceCompass analysis module for Linux containers
(LXC/Docker/Etc...). The information we track is mostly CPU usage by
pid namespace, which would allow the identification of CPU-utilization
related bottlenecks on a Linux container host.
We tried to come up with targeted information to recreate the
container/PID namespace tree of a Linux host and we have modified
lttng-modules to be able to do so :
https://github.com/Selora/lttng-modules
In our analysis, we try to re-use as many information that was already
available in the LTTNG kernel tracer. We build our container/namespace
tree using the tasks and their parent recursively (using only the
pid/vppid/ppid). However, we were unable to have a reliable model
without some light modifications on some tracepoints.
_/
The modifications to the lttng-modulues where the following:/_
We added the PID namespace INode (from /proc/PID/ns/pid) to the LTTNG
statedump tracepoint.
Also, to track new task/containers that would spawn during the tracing
session, we also added multiple fields to the /sched_process_fork/ event :
* Added a VTID field for the children task. This is mandatory in our
analysis, as we keep track of VTID/TID association.
* Added a/parent_ns_inum/ and /child_ns_inum/ field wich represent
the pid namespaces inodes of the parent and child task respectively.
o The /parent_ns_inum/ is "not mandatory" in our analysis, but
it keeps things simple as we don't have to track TID from
parent containers and it keeps the code relatively independant
wheter statedump is enabled or not.
o The /child_ns_inum///IS mandatory, because even if we keep
track of the PID/VPID/PPID/VPPID that have spawned, it is
possible to "inject" a task in an already existing namespace
without repareting it to the child reaper of the container
(this means the task is sent in a namespace, but it is not
part of the process tree of the container of that namespace)
We hope to integrate our analysis to TraceCompass soon, and without
the modification to the LTTNG tracer approved, we would be unable to
proceed throught code review.
We would be really grateful to the community if we could have
feedback, and we will make every modifications possibles to have our
analysis up and working!
The code is supposed to work on kernel version 3.8 through 3.19.
It was tested on 3.18 and 3.19, and I'am going to test it for 3.8 today.
Cheers,
Sebastien & Francis.
>From 46e5eb49eb6f7688d696ef7c7c5108a121c8af33 Mon Sep 17 00:00:00 2001
From: Lrouge <[email protected]>
Date: Wed, 15 Apr 2015 11:53:53 -0400
Subject: [PATCH] Added namespace info in sched_fork and statedump
Modifications to sched_fork :
Added a field for parent and child pid namespace inode (as in /proc/$PID/ns/pid). Also added a field for the child VTID.
Modifications to lttng_statedump_process_state :
Added a field for the pid namespace inode of the task.
---
.../events/lttng-module/lttng-statedump.h | 11 ++++
instrumentation/events/lttng-module/sched.h | 66 +++++++++++++++++++++-
2 files changed, 76 insertions(+), 1 deletion(-)
diff --git a/instrumentation/events/lttng-module/lttng-statedump.h b/instrumentation/events/lttng-module/lttng-statedump.h
index 2369037..db4f990 100644
--- a/instrumentation/events/lttng-module/lttng-statedump.h
+++ b/instrumentation/events/lttng-module/lttng-statedump.h
@@ -8,6 +8,14 @@
#include <linux/nsproxy.h>
#include <linux/pid_namespace.h>
#include <linux/types.h>
+#include <linux/version.h>
+
+
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,0))
+#define lttng_proc_inum ns.inum
+#else
+#define lttng_proc_inum proc_inum
+#endif
LTTNG_TRACEPOINT_EVENT(lttng_statedump_start,
TP_PROTO(struct lttng_session *session),
@@ -60,6 +68,9 @@ LTTNG_TRACEPOINT_EVENT(lttng_statedump_process_state,
ctf_integer(int, submode, submode)
ctf_integer(int, status, status)
ctf_integer(int, ns_level, pid_ns ? pid_ns->level : 0)
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,8,0))
+ ctf_integer(unsigned int, ns_inum, pid_ns ? pid_ns->lttng_proc_inum: 0)
+#endif
)
)
diff --git a/instrumentation/events/lttng-module/sched.h b/instrumentation/events/lttng-module/sched.h
index ac61bce..00a7218 100644
--- a/instrumentation/events/lttng-module/sched.h
+++ b/instrumentation/events/lttng-module/sched.h
@@ -6,12 +6,21 @@
#include "../../../probes/lttng-tracepoint-event.h"
#include <linux/sched.h>
+#include <linux/pid_namespace.h>
#include <linux/binfmts.h>
#include <linux/version.h>
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,9,0))
#include <linux/sched/rt.h>
#endif
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,0))
+#define lttng_proc_inum ns.inum
+#else
+#define lttng_proc_inum proc_inum
+#endif
+
+#define LTTNG_MAX_PID_NS_LEVEL 32
+
#ifndef _TRACE_SCHED_DEF_
#define _TRACE_SCHED_DEF_
@@ -288,19 +297,74 @@ LTTNG_TRACEPOINT_EVENT(sched_process_wait,
* == child_pid, while creation of a thread yields to child_tid !=
* child_pid.
*/
-LTTNG_TRACEPOINT_EVENT(sched_process_fork,
+LTTNG_TRACEPOINT_EVENT_CODE(sched_process_fork,
TP_PROTO(struct task_struct *parent, struct task_struct *child),
TP_ARGS(parent, child),
+ TP_locvar(
+ pid_t vtids[LTTNG_MAX_PID_NS_LEVEL];
+ size_t ns_level;
+ ),
+
+ TP_code(
+ if (child) {
+ int ns_level;
+ struct pid* child_pid;
+ unsigned int i;
+
+ child_pid = task_pid(child);
+ ns_level = child_pid->level + 1;
+ if(ns_level > LTTNG_MAX_PID_NS_LEVEL)
+ {
+ ns_level = LTTNG_MAX_PID_NS_LEVEL;
+ }
+
+ tp_locvar->ns_level = ns_level;
+ for(i = 0; i < ns_level; ++i)
+ {
+ tp_locvar->vtids[i] = child_pid->numbers[i].nr;
+ }
+ }
+ ),
+
TP_FIELDS(
ctf_array_text(char, parent_comm, parent->comm, TASK_COMM_LEN)
ctf_integer(pid_t, parent_tid, parent->pid)
ctf_integer(pid_t, parent_pid, parent->tgid)
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,8,0))
+ ctf_integer(unsigned int, parent_ns_inum,
+ ({
+ unsigned int parent_ns_inum = 0;
+ if (parent) {
+ struct pid_namespace* pid_ns;
+ pid_ns = task_active_pid_ns(parent);
+ if(pid_ns) {
+ parent_ns_inum = pid_ns->lttng_proc_inum;
+ }
+ }
+ parent_ns_inum;
+ }))
+#endif
ctf_array_text(char, child_comm, child->comm, TASK_COMM_LEN)
ctf_integer(pid_t, child_tid, child->pid)
+ ctf_sequence(pid_t, vtids, tp_locvar->vtids, u8, tp_locvar->ns_level)
ctf_integer(pid_t, child_pid, child->tgid)
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,8,0))
+ ctf_integer(unsigned int, child_ns_inum,
+ ({
+ unsigned int child_ns_inum = 0;
+ if (child) {
+ struct pid_namespace* pid_ns;
+ pid_ns = task_active_pid_ns(child);
+ if(pid_ns) {
+ child_ns_inum = pid_ns->lttng_proc_inum;
+ }
+ }
+ child_ns_inum;
+ }))
+#endif
)
)
--
2.3.5
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