From ed1777de25e45bfb58fad63341904f8a77911785 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 10 Aug 2016 11:23:44 -0400 Subject: [PATCH] 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 --- include/trace/events/cgroup.h | 163 ++++++++++++++++++++++++++++++++++ kernel/cgroup.c | 25 ++++++ 2 files changed, 188 insertions(+) create mode 100644 include/trace/events/cgroup.h diff --git a/include/trace/events/cgroup.h b/include/trace/events/cgroup.h new file mode 100644 index 000000000000..ab68640a18d0 --- /dev/null +++ b/include/trace/events/cgroup.h @@ -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 +#include + +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 diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3861161e460f..5e2e81ad9175 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -64,6 +64,9 @@ #include #include +#define CREATE_TRACE_POINTS +#include + /* * 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; }