A pmonr is the per-package component of a monr. This patch only adds
initialization/destruction of pmonrs. Future patches explain their
usage and add functionality.
CPU hotplug is supported by initializing/terminating all pmonrs in
monr hierarchy when first/last CPU in package goes online/offline.
Signed-off-by: David Carrillo-Cisneros <davi...@google.com>
---
arch/x86/events/intel/cmt.c | 161 +++++++++++++++++++++++++++++++++++++++++++-
arch/x86/events/intel/cmt.h | 20 +++++-
2 files changed, 177 insertions(+), 4 deletions(-)
diff --git a/arch/x86/events/intel/cmt.c b/arch/x86/events/intel/cmt.c
index 39f4bfa..06e6325 100644
--- a/arch/x86/events/intel/cmt.c
+++ b/arch/x86/events/intel/cmt.c
@@ -103,13 +103,49 @@ static void monr_hrchy_release_locks(unsigned long *flags)
raw_local_irq_restore(*flags);
}
+static inline struct pmonr *pkgd_pmonr(struct pkg_data *pkgd, struct monr
*monr)
+{
+#ifdef CONFIG_LOCKDEP
+ bool safe = lockdep_is_held(&cmt_mutex) ||
+ lockdep_is_held(&pkgd->lock) ||
+ rcu_read_lock_held();
+#endif
+
+ return rcu_dereference_check(monr->pmonrs[pkgd->pkgid], safe);
+}
+
+static struct pmonr *pmonr_alloc(struct pkg_data *pkgd)
+{
+ struct pmonr *pmonr;
+ int cpu_node = cpu_to_node(pkgd->work_cpu);
+
+ pmonr = kzalloc_node(sizeof(*pmonr), GFP_KERNEL, cpu_node);
+ if (!pmonr)
+ return ERR_PTR(-ENOMEM);
+
+ pmonr->pkgd = pkgd;
+
+ return pmonr;
+}
+
static void monr_dealloc(struct monr *monr)
{
+ u16 p, nr_pkgs = topology_max_packages();
+
+ for (p = 0; p < nr_pkgs; p++) {
+ /* out of monr_hrchy, so no need for rcu or lock protection. */
+ if (!monr->pmonrs[p])
+ continue;
+ kfree(monr->pmonrs[p]);
+ }
kfree(monr);
}
+/* Alloc monr with all pmonrs in Off state. */
static struct monr *monr_alloc(void)
{
+ struct pkg_data *pkgd = NULL;
+ struct pmonr *pmonr;
struct monr *monr;
lockdep_assert_held(&cmt_mutex);
@@ -122,6 +158,28 @@ static struct monr *monr_alloc(void)
INIT_LIST_HEAD(&monr->children);
INIT_LIST_HEAD(&monr->parent_entry);
+ monr->pmonrs = kcalloc(topology_max_packages(),
+ sizeof(pmonr), GFP_KERNEL);
+ if (!monr->pmonrs) {
+ monr_dealloc(monr);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ /*
+ * Do not create pmonrs for unitialized packages.
+ * Protected from initialization of new pkgs by cqm_mutex
+ */
+ while ((pkgd = cmt_pkgs_data_next_rcu(pkgd))) {
+ pmonr = pmonr_alloc(pkgd);
+ if (IS_ERR(pmonr)) {
+ monr_dealloc(monr);
+ return ERR_CAST(pmonr);
+ }
+ pmonr->monr = monr;
+ /* safe to assign since pmonr is not in monr_hrchy. */
+ RCU_INIT_POINTER(monr->pmonrs[pkgd->pkgid], pmonr);
+ }
+
return monr;
}
@@ -318,6 +376,69 @@ static int mon_group_setup_event(struct perf_event *event)
return monr_hrchy_attach_event(event);
}
+static struct monr *monr_next_child(struct monr *pos, struct monr *parent)
+{
+ if (!pos)
+ return list_first_entry_or_null(
+ &parent->children, struct monr, parent_entry);
+ if (list_is_last(&pos->parent_entry, &parent->children))
+ return NULL;
+
+ return list_next_entry(pos, parent_entry);
+}
+
+static struct monr *monr_next_descendant_pre(struct monr *pos,
+ struct monr *root)
+{
+ struct monr *next;
+
+ if (!pos)
+ return root;
+
+ next = monr_next_child(NULL, pos);
+ if (next)
+ return next;
+
+ while (pos != root) {
+ next = monr_next_child(pos, pos->parent);
+ if (next)
+ return next;
+ pos = pos->parent;
+ }
+
+ return NULL;
+}
+
+static struct monr *monr_leftmost_descendant(struct monr *pos)
+{
+ struct monr *last;
+
+ do {
+ last = pos;
+ pos = monr_next_child(NULL, pos);
+ } while (pos);
+
+ return last;
+}
+
+static struct monr *monr_next_descendant_post(struct monr *pos,
+ struct monr *root)
+{
+ struct monr *next;
+
+ if (!pos)
+ return monr_leftmost_descendant(root);
+
+ if (pos == root)
+ return NULL;
+
+ next = monr_next_child(pos, pos->parent);
+ if (next)
+ return monr_leftmost_descendant(next);
+
+ return pos->parent;
+}
+
static void intel_cmt_event_read(struct perf_event *event)
{
}
@@ -482,14 +603,29 @@ static struct pkg_data *alloc_pkg_data(int cpu)
static void __terminate_pkg_data(struct pkg_data *pkgd)
{
+ struct monr *pos = NULL;
+ unsigned long flags;
+
lockdep_assert_held(&cmt_mutex);
+ raw_spin_lock_irqsave(&pkgd->lock, flags);
+ /* post-order traversal guarantees pos to be leaf of monr hierarchy. */
+ while ((pos = monr_next_descendant_post(pos, monr_hrchy_root)))
+ RCU_INIT_POINTER(pos->pmonrs[pkgd->pkgid], NULL);
+
+ raw_spin_unlock_irqrestore(&pkgd->lock, flags);
+
+ synchronize_rcu();
+
free_pkg_data(pkgd);
}
static int init_pkg_data(int cpu)
{
+ struct monr *pos = NULL;
struct pkg_data *pkgd;
+ struct pmonr *pmonr;
+ int err = 0;
u16 pkgid = topology_logical_package_id(cpu);
lockdep_assert_held(&cmt_mutex);
@@ -502,10 +638,28 @@ static int init_pkg_data(int cpu)
if (IS_ERR(pkgd))
return PTR_ERR(pkgd);
- rcu_assign_pointer(cmt_pkgs_data[pkgid], pkgd);
- synchronize_rcu();
+ while ((pos = monr_next_descendant_pre(pos, monr_hrchy_root))) {
+ pmonr = pmonr_alloc(pkgd);
+ if (IS_ERR(pmonr)) {
+ err = PTR_ERR(pmonr);
+ break;
+ }
+ pmonr->monr = pos;
+ /*
+ * No need to protect pmonrs since this pkgd is
+ * not set in cmt_pkgs_data yet.
+ */
+ RCU_INIT_POINTER(pos->pmonrs[pkgid], pmonr);
+ }
- return 0;
+ if (err) {
+ __terminate_pkg_data(pkgd);
+ } else {
+ rcu_assign_pointer(cmt_pkgs_data[pkgid], pkgd);
+ synchronize_rcu();
+ }
+
+ return err;
}
static int intel_cmt_hp_online_enter(unsigned int cpu)
@@ -604,6 +758,7 @@ static int __init cmt_alloc(void)
if (!cmt_pkgs_data)
return -ENOMEM;
+ /* won't alloc any pmonr since no cmt_pkg_data is initialized yet. */
mutex_lock(&cmt_mutex);
monr_hrchy_root = monr_alloc();
mutex_unlock(&cmt_mutex);
diff --git a/arch/x86/events/intel/cmt.h b/arch/x86/events/intel/cmt.h
index 46e8335..7f3a7b8 100644
--- a/arch/x86/events/intel/cmt.h
+++ b/arch/x86/events/intel/cmt.h
@@ -27,6 +27,9 @@
* and to make possible to capture dependencies between threads in the same
* cgroup or process.
*
+ * Each monr has a package monr (pmonr) for each package with at least one
+ * online cpu. The pmonr handles the CMT and MBM monitoring within its package.
+ *
*
* Locking
*
@@ -38,8 +41,19 @@
* cgroup start/stop.
* - Hold pkg->mutex and pkg->lock in _all_ active packages to traverse or
* change the monr hierarchy.
- * - pkgd->lock: Hold in current package to access that pkgd's members.
+ * - pkgd->lock: Hold in current package to access that pkgd's members. Hold
+ * a pmonr's package pkgd->lock for non-atomic access to pmonr.
+ */
+
+/**
+ * struct pmonr - per-package componet of MONitored Resources (monr).
+ * @monr: The monr that contains this pmonr.
+ * @pkgd: The package data associated with this pmonr.
*/
+struct pmonr {
+ struct monr *monr;
+ struct pkg_data *pkgd;
+};
/**
* struct pkg_data - Per-package CMT data.
@@ -65,6 +79,7 @@ struct pkg_data {
* struct monr - MONitored Resource.
* @mon_events: The head of event's group that use this monr,
if any.
* @entry: List entry into cmt_event_monrs.
+ * @pmonrs: Per-package pmonrs.
* @parent: Parent in monr hierarchy.
* @children: List of children in monr hierarchy.
* @parent_entry: Entry in parent's children list.
@@ -72,10 +87,13 @@ struct pkg_data {
* An monr is assigned to every CMT event and/or monitored cgroups when
* monitoring is activated and that instance's address do not change during
* the lifetime of the event or cgroup.
+ *
+ * On initialization, all monr's pmonrs start in Off state.
*/
struct monr {
struct perf_event *mon_events;
struct list_head entry;
+ struct pmonr **pmonrs;
struct monr *parent;
struct list_head children;
--
2.8.0.rc3.226.g39d4020
