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cgroup: update debug controller to print out thread mode information

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Update debug controller so that it prints out debug info about thread
mode.

 1) The relationship between proc_cset and threaded_csets are displayed.
 2) The status of being a thread root or threaded cgroup is displayed.

This patch is extracted from Waiman's larger patch.

v2: - Removed [thread root] / [threaded] from debug.cgroup_css_links
      file as the same information is available from cgroup.type.
      Suggested by Waiman.
    - Threaded marking is moved to the previous patch.

Patch-originally-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Waiman Long 2017-07-21 11:14:51 -04:00 committed by Tejun Heo
parent 8cfd8147df
commit 7a0cf0e74a
3 changed files with 41 additions and 15 deletions
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2
kernel/cgroup/cgroup-internal.h
View File

@ -153,6 +153,8 @@ static inline void get_css_set(struct css_set *cset)
bool cgroup_ssid_enabled(int ssid);
bool cgroup_on_dfl(const struct cgroup *cgrp);
bool cgroup_is_thread_root(struct cgroup *cgrp);
bool cgroup_is_threaded(struct cgroup *cgrp);
struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
struct cgroup *task_cgroup_from_root(struct task_struct *task,

4
kernel/cgroup/cgroup.c
View File

@ -333,7 +333,7 @@ static bool cgroup_has_tasks(struct cgroup *cgrp)
return cgrp->nr_populated_csets;
}
static bool cgroup_is_threaded(struct cgroup *cgrp)
bool cgroup_is_threaded(struct cgroup *cgrp)
{
return cgrp->dom_cgrp != cgrp;
}
@ -372,7 +372,7 @@ static bool cgroup_can_be_thread_root(struct cgroup *cgrp)
}
/* is @cgrp root of a threaded subtree? */
static bool cgroup_is_thread_root(struct cgroup *cgrp)
bool cgroup_is_thread_root(struct cgroup *cgrp)
{
/* thread root should be a domain */
if (cgroup_is_threaded(cgrp))

50
kernel/cgroup/debug.c
View File

@ -114,27 +114,49 @@ static int cgroup_css_links_read(struct seq_file *seq, void *v)
{
struct cgroup_subsys_state *css = seq_css(seq);
struct cgrp_cset_link *link;
int dead_cnt = 0, extra_refs = 0;
int dead_cnt = 0, extra_refs = 0, threaded_csets = 0;
spin_lock_irq(&css_set_lock);
list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
struct css_set *cset = link->cset;
struct task_struct *task;
int count = 0;
int refcnt = refcount_read(&cset->refcount);
seq_printf(seq, " %d", refcnt);
if (refcnt - cset->nr_tasks > 0) {
int extra = refcnt - cset->nr_tasks;
/*
* Print out the proc_cset and threaded_cset relationship
* and highlight difference between refcount and task_count.
*/
seq_printf(seq, "css_set %pK", cset);
if (rcu_dereference_protected(cset->dom_cset, 1) != cset) {
threaded_csets++;
seq_printf(seq, "=>%pK", cset->dom_cset);
}
if (!list_empty(&cset->threaded_csets)) {
struct css_set *tcset;
int idx = 0;
seq_printf(seq, " +%d", extra);
/*
* Take out the one additional reference in
* init_css_set.
*/
if (cset == &init_css_set)
extra--;
extra_refs += extra;
list_for_each_entry(tcset, &cset->threaded_csets,
threaded_csets_node) {
seq_puts(seq, idx ? "," : "<=");
seq_printf(seq, "%pK", tcset);
idx++;
}
} else {
seq_printf(seq, " %d", refcnt);
if (refcnt - cset->nr_tasks > 0) {
int extra = refcnt - cset->nr_tasks;
seq_printf(seq, " +%d", extra);
/*
* Take out the one additional reference in
* init_css_set.
*/
if (cset == &init_css_set)
extra--;
extra_refs += extra;
}
}
seq_puts(seq, "\n");
@ -163,10 +185,12 @@ static int cgroup_css_links_read(struct seq_file *seq, void *v)
}
spin_unlock_irq(&css_set_lock);
if (!dead_cnt && !extra_refs)
if (!dead_cnt && !extra_refs && !threaded_csets)
return 0;
seq_puts(seq, "\n");
if (threaded_csets)
seq_printf(seq, "threaded css_sets = %d\n", threaded_csets);
if (extra_refs)
seq_printf(seq, "extra references = %d\n", extra_refs);
if (dead_cnt)