proc: Add an interface to get all the tasks that share a core
Core-scheduling allows tasks to share a core. The per-process interface
is the prctl(2) PR_SET_CORE_SCHED added in earlier patches which allows
a process to set or change the set of processes it is allowed to share a
core with.
This proc file is intended to help with introspection and testing to
determine which other processes does it share a core with.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
diff --git a/fs/proc/base.c b/fs/proc/base.c
index a8a3879..9a55e90 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3206,6 +3206,9 @@
#ifdef CONFIG_PROC_PID_ARCH_STATUS
ONE("arch_status", S_IRUGO, proc_pid_arch_status),
#endif
+#ifdef CONFIG_SCHED_CORE
+ ONE("coresched_tasks", S_IRUGO, sched_core_proc_tasks),
+#endif
};
static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 58d01eb..11bc110 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1988,8 +1988,12 @@
#ifdef CONFIG_SCHED_CORE
int sched_core_join_pid(pid_t pid);
+int sched_core_proc_tasks(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *p);
#else
static int sched_core_join_pid(pid_t pid) { return -ENOTSUPP; }
+static int sched_core_proc_tasks(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *p) { return -ENOTSUPP; }
#endif
void __exit_umh(struct task_struct *tsk);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2f98e46..e0c793e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3408,6 +3408,25 @@
}
}
+/* Go through all TGIDs and print ones with @p's tag. */
+int sched_core_proc_tasks(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *tsk)
+{
+ struct task_struct *p;
+
+ rcu_read_lock();
+ mutex_lock(&sched_core_mutex);
+ for_each_process(p) {
+ if (p == tsk)
+ continue;
+ if (tsk->core_cookie == p->core_cookie)
+ seq_printf(m, "%d\n", p->pid);
+ }
+ mutex_unlock(&sched_core_mutex);
+ rcu_read_unlock();
+
+ return 0;
+}
#endif /* CONFIG_SCHED_CORE */
/*
