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@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Jinshi Chen <jinshi.chen@intel.com>
Link: https://lkml.kernel.org/r/20200115092851.14761-1-yu.c.chen@intel.com

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5e89499..6e17a68 100644 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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"
@@ -3060,6 +3061,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 #endif
 #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),
@@ -3460,6 +3464,9 @@ static const struct pid_entry tid_base_stuff[] = {
 #endif
 #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),

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
new file mode 100644 (file)
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 */