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Subject[tip:x86/cache] x86/intel_rdt/cqm: Add tasks file support
Commit-ID:  d6aaba615a482ce7d3ec218cf7b8d02d0d5753b8
Gitweb: http://git.kernel.org/tip/d6aaba615a482ce7d3ec218cf7b8d02d0d5753b8
Author: Vikas Shivappa <vikas.shivappa@linux.intel.com>
AuthorDate: Tue, 25 Jul 2017 14:14:34 -0700
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 1 Aug 2017 22:41:24 +0200

x86/intel_rdt/cqm: Add tasks file support

The root directory, ctrl_mon and monitor groups are populated
with a read/write file named "tasks". When read, it shows all the task
IDs assigned to the resource group.

Tasks can be added to groups by writing the PID to the file. A task can
be present in one "ctrl_mon" group "and" one "monitor" group. IOW a
PID_x can be seen in a ctrl_mon group and a monitor group at the same
time. When a task is added to a ctrl_mon group, it is automatically
removed from the previous ctrl_mon group where it belonged. Similarly if
a task is moved to a monitor group it is removed from the previous
monitor group . Also since the monitor groups can only have subset of
tasks of parent ctrl_mon group, a task can be moved to a monitor group
only if its already present in the parent ctrl_mon group.

Task membership is indicated by a new field in the task_struct "u32
rmid" which holds the RMID for the task. RMID=0 is reserved for the
default root group where the tasks belong to at mount.

[tony: zero the rmid if rdtgroup was deleted when task was being moved]

Signed-off-by: Tony Luck <tony.luck@linux.intel.com>
Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Cc: vikas.shivappa@intel.com
Cc: ak@linux.intel.com
Cc: davidcc@google.com
Cc: reinette.chatre@intel.com
Link: http://lkml.kernel.org/r/1501017287-28083-16-git-send-email-vikas.shivappa@linux.intel.com

---
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 19 +++++++++++++++++--
include/linux/sched.h | 1 +
2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 8404054..aedad1d 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -314,6 +314,7 @@ static void move_myself(struct callback_head *head)
if (atomic_dec_and_test(&rdtgrp->waitcount) &&
(rdtgrp->flags & RDT_DELETED)) {
current->closid = 0;
+ current->rmid = 0;
kfree(rdtgrp);
}

@@ -352,7 +353,20 @@ static int __rdtgroup_move_task(struct task_struct *tsk,
atomic_dec(&rdtgrp->waitcount);
kfree(callback);
} else {
- tsk->closid = rdtgrp->closid;
+ /*
+ * For ctrl_mon groups move both closid and rmid.
+ * For monitor groups, can move the tasks only from
+ * their parent CTRL group.
+ */
+ if (rdtgrp->type == RDTCTRL_GROUP) {
+ tsk->closid = rdtgrp->closid;
+ tsk->rmid = rdtgrp->mon.rmid;
+ } else if (rdtgrp->type == RDTMON_GROUP) {
+ if (rdtgrp->mon.parent->closid == tsk->closid)
+ tsk->rmid = rdtgrp->mon.rmid;
+ else
+ ret = -EINVAL;
+ }
}
return ret;
}
@@ -432,7 +446,8 @@ static void show_rdt_tasks(struct rdtgroup *r, struct seq_file *s)

rcu_read_lock();
for_each_process_thread(p, t) {
- if (t->closid == r->closid)
+ if ((r->type == RDTCTRL_GROUP && t->closid == r->closid) ||
+ (r->type == RDTMON_GROUP && t->rmid == r->mon.rmid))
seq_printf(s, "%d\n", t->pid);
}
rcu_read_unlock();
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8839fd0..067a41a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -900,6 +900,7 @@ struct task_struct {
#endif
#ifdef CONFIG_INTEL_RDT
u32 closid;
+ u32 rmid;
#endif
#ifdef CONFIG_FUTEX
struct robust_list_head __user *robust_list;
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