cgroup: add tracepoints for basic operations

Debugging what goes wrong with cgroup setup can get hairy.  Add
tracepoints for cgroup hierarchy mount, cgroup creation/destruction
and task migration operations for better visibility.

Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2016-08-10 11:23:44 -04:00
parent 4c737b41de
commit ed1777de25
2 changed files with 188 additions and 0 deletions

View File

@ -0,0 +1,163 @@
#undef TRACE_SYSTEM
#define TRACE_SYSTEM cgroup
#if !defined(_TRACE_CGROUP_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_CGROUP_H
#include <linux/cgroup.h>
#include <linux/tracepoint.h>
DECLARE_EVENT_CLASS(cgroup_root,
TP_PROTO(struct cgroup_root *root),
TP_ARGS(root),
TP_STRUCT__entry(
__field( int, root )
__field( u16, ss_mask )
__string( name, root->name )
),
TP_fast_assign(
__entry->root = root->hierarchy_id;
__entry->ss_mask = root->subsys_mask;
__assign_str(name, root->name);
),
TP_printk("root=%d ss_mask=%#x name=%s",
__entry->root, __entry->ss_mask, __get_str(name))
);
DEFINE_EVENT(cgroup_root, cgroup_setup_root,
TP_PROTO(struct cgroup_root *root),
TP_ARGS(root)
);
DEFINE_EVENT(cgroup_root, cgroup_destroy_root,
TP_PROTO(struct cgroup_root *root),
TP_ARGS(root)
);
DEFINE_EVENT(cgroup_root, cgroup_remount,
TP_PROTO(struct cgroup_root *root),
TP_ARGS(root)
);
DECLARE_EVENT_CLASS(cgroup,
TP_PROTO(struct cgroup *cgrp),
TP_ARGS(cgrp),
TP_STRUCT__entry(
__field( int, root )
__field( int, id )
__field( int, level )
__dynamic_array(char, path,
cgrp->kn ? cgroup_path(cgrp, NULL, 0) + 1
: strlen("(null)"))
),
TP_fast_assign(
__entry->root = cgrp->root->hierarchy_id;
__entry->id = cgrp->id;
__entry->level = cgrp->level;
if (cgrp->kn)
cgroup_path(cgrp, __get_dynamic_array(path),
__get_dynamic_array_len(path));
else
__assign_str(path, "(null)");
),
TP_printk("root=%d id=%d level=%d path=%s",
__entry->root, __entry->id, __entry->level, __get_str(path))
);
DEFINE_EVENT(cgroup, cgroup_mkdir,
TP_PROTO(struct cgroup *cgroup),
TP_ARGS(cgroup)
);
DEFINE_EVENT(cgroup, cgroup_rmdir,
TP_PROTO(struct cgroup *cgroup),
TP_ARGS(cgroup)
);
DEFINE_EVENT(cgroup, cgroup_release,
TP_PROTO(struct cgroup *cgroup),
TP_ARGS(cgroup)
);
DEFINE_EVENT(cgroup, cgroup_rename,
TP_PROTO(struct cgroup *cgroup),
TP_ARGS(cgroup)
);
DECLARE_EVENT_CLASS(cgroup_migrate,
TP_PROTO(struct cgroup *dst_cgrp, struct task_struct *task, bool threadgroup),
TP_ARGS(dst_cgrp, task, threadgroup),
TP_STRUCT__entry(
__field( int, dst_root )
__field( int, dst_id )
__field( int, dst_level )
__dynamic_array(char, dst_path,
dst_cgrp->kn ? cgroup_path(dst_cgrp, NULL, 0) + 1
: strlen("(null)"))
__field( int, pid )
__string( comm, task->comm )
),
TP_fast_assign(
__entry->dst_root = dst_cgrp->root->hierarchy_id;
__entry->dst_id = dst_cgrp->id;
__entry->dst_level = dst_cgrp->level;
if (dst_cgrp->kn)
cgroup_path(dst_cgrp, __get_dynamic_array(dst_path),
__get_dynamic_array_len(dst_path));
else
__assign_str(dst_path, "(null)");
__entry->pid = task->pid;
__assign_str(comm, task->comm);
),
TP_printk("dst_root=%d dst_id=%d dst_level=%d dst_path=%s pid=%d comm=%s",
__entry->dst_root, __entry->dst_id, __entry->dst_level,
__get_str(dst_path), __entry->pid, __get_str(comm))
);
DEFINE_EVENT(cgroup_migrate, cgroup_attach_task,
TP_PROTO(struct cgroup *dst_cgrp, struct task_struct *task, bool threadgroup),
TP_ARGS(dst_cgrp, task, threadgroup)
);
DEFINE_EVENT(cgroup_migrate, cgroup_transfer_tasks,
TP_PROTO(struct cgroup *dst_cgrp, struct task_struct *task, bool threadgroup),
TP_ARGS(dst_cgrp, task, threadgroup)
);
#endif /* _TRACE_CGROUP_H */
/* This part must be outside protection */
#include <trace/define_trace.h>

View File

@ -64,6 +64,9 @@
#include <linux/file.h>
#include <net/sock.h>
#define CREATE_TRACE_POINTS
#include <trace/events/cgroup.h>
/*
* pidlists linger the following amount before being destroyed. The goal
* is avoiding frequent destruction in the middle of consecutive read calls
@ -1176,6 +1179,8 @@ static void cgroup_destroy_root(struct cgroup_root *root)
struct cgroup *cgrp = &root->cgrp;
struct cgrp_cset_link *link, *tmp_link;
trace_cgroup_destroy_root(root);
cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
BUG_ON(atomic_read(&root->nr_cgrps));
@ -1874,6 +1879,9 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
strcpy(root->release_agent_path, opts.release_agent);
spin_unlock(&release_agent_path_lock);
}
trace_cgroup_remount(root);
out_unlock:
kfree(opts.release_agent);
kfree(opts.name);
@ -2031,6 +2039,8 @@ static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
if (ret)
goto destroy_root;
trace_cgroup_setup_root(root);
/*
* There must be no failure case after here, since rebinding takes
* care of subsystems' refcounts, which are explicitly dropped in
@ -2825,6 +2835,10 @@ static int cgroup_attach_task(struct cgroup *dst_cgrp,
ret = cgroup_migrate(leader, threadgroup, dst_cgrp->root);
cgroup_migrate_finish(&preloaded_csets);
if (!ret)
trace_cgroup_attach_task(dst_cgrp, leader, threadgroup);
return ret;
}
@ -3587,6 +3601,8 @@ static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
mutex_lock(&cgroup_mutex);
ret = kernfs_rename(kn, new_parent, new_name_str);
if (!ret)
trace_cgroup_rename(cgrp);
mutex_unlock(&cgroup_mutex);
@ -4355,6 +4371,8 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
if (task) {
ret = cgroup_migrate(task, false, to->root);
if (!ret)
trace_cgroup_transfer_tasks(to, task, false);
put_task_struct(task);
}
} while (task && !ret);
@ -5020,6 +5038,8 @@ static void css_release_work_fn(struct work_struct *work)
ss->css_released(css);
} else {
/* cgroup release path */
trace_cgroup_release(cgrp);
cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
cgrp->id = -1;
@ -5306,6 +5326,8 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
if (ret)
goto out_destroy;
trace_cgroup_mkdir(cgrp);
/* let's create and online css's */
kernfs_activate(kn);
@ -5481,6 +5503,9 @@ static int cgroup_rmdir(struct kernfs_node *kn)
ret = cgroup_destroy_locked(cgrp);
if (!ret)
trace_cgroup_rmdir(cgrp);
cgroup_kn_unlock(kn);
return ret;
}