[tip: x86/cache] x86/resctrl: Add task resctrl information display

From: tip-bot2 for Chen Yu
Date: Mon Jan 20 2020 - 10:45:31 EST

The following commit has been merged into the x86/cache branch of tip:

Commit-ID: e79f15a4598c1f3f3f7f3319ca308c63c91fdaf2
Gitweb: https://git.kernel.org/tip/e79f15a4598c1f3f3f7f3319ca308c63c91fdaf2
Author: Chen Yu <yu.c.chen@xxxxxxxxx>
AuthorDate: Wed, 15 Jan 2020 17:28:51 +08:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Mon, 20 Jan 2020 16:19:10 +01:00

x86/resctrl: Add task resctrl information display

Monitoring tools that want to find out which resctrl control and monitor
groups a task belongs to must currently read the "tasks" file in every
group until they locate the process ID.

Add an additional file /proc/{pid}/cpu_resctrl_groups to provide this
information:

1) res:
mon:

resctrl is not available.

2) res:/
mon:

Task is part of the root resctrl control group, and it is not associated
to any monitor group.

3) res:/
mon:mon0

Task is part of the root resctrl control group and monitor group mon0.

4) res:group0
mon:

Task is part of resctrl control group group0, and it is not associated
to any monitor group.

5) res:group0
mon:mon1

Task is part of resctrl control group group0 and monitor group mon1.

Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Tested-by: Jinshi Chen <jinshi.chen@xxxxxxxxx>
Link: https://lkml.kernel.org/r/20200115092851.14761-1-yu.c.chen@xxxxxxxxx
---
arch/x86/Kconfig | 1 +-
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 86 +++++++++++++++++++++++++-
fs/proc/Kconfig | 4 +-
fs/proc/base.c | 7 ++-
include/linux/resctrl.h | 14 ++++-
5 files changed, 112 insertions(+)
create mode 100644 include/linux/resctrl.h

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5e89499..6e17a68 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -456,6 +456,7 @@ config X86_CPU_RESCTRL
bool "x86 CPU resource control support"
depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
select KERNFS
+ select PROC_CPU_RESCTRL if PROC_FS
help
Enable x86 CPU resource control support.

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 205925d..5b3ba83 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -729,6 +729,92 @@ static int rdtgroup_tasks_show(struct kernfs_open_file *of,
return ret;
}

+#ifdef CONFIG_PROC_CPU_RESCTRL
+
+/*
+ * A task can only be part of one resctrl control group and of one monitor
+ * group which is associated to that control group.
+ *
+ * 1) res:
+ * mon:
+ *
+ * resctrl is not available.
+ *
+ * 2) res:/
+ * mon:
+ *
+ * Task is part of the root resctrl control group, and it is not associated
+ * to any monitor group.
+ *
+ * 3) res:/
+ * mon:mon0
+ *
+ * Task is part of the root resctrl control group and monitor group mon0.
+ *
+ * 4) res:group0
+ * mon:
+ *
+ * Task is part of resctrl control group group0, and it is not associated
+ * to any monitor group.
+ *
+ * 5) res:group0
+ * mon:mon1
+ *
+ * Task is part of resctrl control group group0 and monitor group mon1.
+ */
+int proc_resctrl_show(struct seq_file *s, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *tsk)
+{
+ struct rdtgroup *rdtg;
+ int ret = 0;
+
+ mutex_lock(&rdtgroup_mutex);
+
+ /* Return empty if resctrl has not been mounted. */
+ if (!static_branch_unlikely(&rdt_enable_key)) {
+ seq_puts(s, "res:\nmon:\n");
+ goto unlock;
+ }
+
+ list_for_each_entry(rdtg, &rdt_all_groups, rdtgroup_list) {
+ struct rdtgroup *crg;
+
+ /*
+ * Task information is only relevant for shareable
+ * and exclusive groups.
+ */
+ if (rdtg->mode != RDT_MODE_SHAREABLE &&
+ rdtg->mode != RDT_MODE_EXCLUSIVE)
+ continue;
+
+ if (rdtg->closid != tsk->closid)
+ continue;
+
+ seq_printf(s, "res:%s%s\n", (rdtg == &rdtgroup_default) ? "/" : "",
+ rdtg->kn->name);
+ seq_puts(s, "mon:");
+ list_for_each_entry(crg, &rdtg->mon.crdtgrp_list,
+ mon.crdtgrp_list) {
+ if (tsk->rmid != crg->mon.rmid)
+ continue;
+ seq_printf(s, "%s", crg->kn->name);
+ break;
+ }
+ seq_putc(s, '\n');
+ goto unlock;
+ }
+ /*
+ * The above search should succeed. Otherwise return
+ * with an error.
+ */
+ ret = -ENOENT;
+unlock:
+ mutex_unlock(&rdtgroup_mutex);
+
+ return ret;
+}
+#endif
+
static int rdt_last_cmd_status_show(struct kernfs_open_file *of,
struct seq_file *seq, void *v)
{
diff --git a/fs/proc/Kconfig b/fs/proc/Kconfig
index 733881a..27ef84d 100644
--- a/fs/proc/Kconfig
+++ b/fs/proc/Kconfig
@@ -103,3 +103,7 @@ config PROC_CHILDREN
config PROC_PID_ARCH_STATUS
def_bool n
depends on PROC_FS
+
+config PROC_CPU_RESCTRL
+ def_bool n
+ depends on PROC_FS
diff --git a/fs/proc/base.c b/fs/proc/base.c
index ebea950..bbffd65 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -94,6 +94,7 @@
#include <linux/sched/debug.h>
#include <linux/sched/stat.h>
#include <linux/posix-timers.h>
+#include <linux/resctrl.h>
#include <trace/events/oom.h>
#include "internal.h"
#include "fd.h"
@@ -3061,6 +3062,9 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_CGROUPS
ONE("cgroup", S_IRUGO, proc_cgroup_show),
#endif
+#ifdef CONFIG_PROC_CPU_RESCTRL
+ ONE("cpu_resctrl_groups", S_IRUGO, proc_resctrl_show),
+#endif
ONE("oom_score", S_IRUGO, proc_oom_score),
REG("oom_adj", S_IRUGO|S_IWUSR, proc_oom_adj_operations),
REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
@@ -3461,6 +3465,9 @@ static const struct pid_entry tid_base_stuff[] = {
#ifdef CONFIG_CGROUPS
ONE("cgroup", S_IRUGO, proc_cgroup_show),
#endif
+#ifdef CONFIG_PROC_CPU_RESCTRL
+ ONE("cpu_resctrl_groups", S_IRUGO, proc_resctrl_show),
+#endif
ONE("oom_score", S_IRUGO, proc_oom_score),
REG("oom_adj", S_IRUGO|S_IWUSR, proc_oom_adj_operations),
REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
new file mode 100644
index 0000000..daf5cf6
--- /dev/null
+++ b/include/linux/resctrl.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _RESCTRL_H
+#define _RESCTRL_H
+
+#ifdef CONFIG_PROC_CPU_RESCTRL
+
+int proc_resctrl_show(struct seq_file *m,
+ struct pid_namespace *ns,
+ struct pid *pid,
+ struct task_struct *tsk);
+
+#endif
+
+#endif /* _RESCTRL_H */