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-rw-r--r--arch/x86/kernel/cpu/perf_event.c45
-rw-r--r--arch/x86/kernel/cpu/perf_event.h30
-rw-r--r--arch/x86/kernel/cpu/perf_event_amd.c2
3 files changed, 72 insertions, 5 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 5a469d3d0c66..fa6fdec5afbc 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -499,11 +499,16 @@ struct sched_state {
unsigned long used[BITS_TO_LONGS(X86_PMC_IDX_MAX)];
};
+/* Total max is X86_PMC_IDX_MAX, but we are O(n!) limited */
+#define SCHED_STATES_MAX 2
+
struct perf_sched {
int max_weight;
int max_events;
struct event_constraint **constraints;
struct sched_state state;
+ int saved_states;
+ struct sched_state saved[SCHED_STATES_MAX];
};
/*
@@ -529,11 +534,34 @@ static void perf_sched_init(struct perf_sched *sched, struct event_constraint **
sched->state.unassigned = num;
}
+static void perf_sched_save_state(struct perf_sched *sched)
+{
+ if (WARN_ON_ONCE(sched->saved_states >= SCHED_STATES_MAX))
+ return;
+
+ sched->saved[sched->saved_states] = sched->state;
+ sched->saved_states++;
+}
+
+static bool perf_sched_restore_state(struct perf_sched *sched)
+{
+ if (!sched->saved_states)
+ return false;
+
+ sched->saved_states--;
+ sched->state = sched->saved[sched->saved_states];
+
+ /* continue with next counter: */
+ clear_bit(sched->state.counter++, sched->state.used);
+
+ return true;
+}
+
/*
* Select a counter for the current event to schedule. Return true on
* success.
*/
-static bool perf_sched_find_counter(struct perf_sched *sched)
+static bool __perf_sched_find_counter(struct perf_sched *sched)
{
struct event_constraint *c;
int idx;
@@ -557,6 +585,19 @@ static bool perf_sched_find_counter(struct perf_sched *sched)
if (idx >= X86_PMC_IDX_MAX)
return false;
+ if (c->overlap)
+ perf_sched_save_state(sched);
+
+ return true;
+}
+
+static bool perf_sched_find_counter(struct perf_sched *sched)
+{
+ while (!__perf_sched_find_counter(sched)) {
+ if (!perf_sched_restore_state(sched))
+ return false;
+ }
+
return true;
}
@@ -1250,7 +1291,7 @@ static int __init init_hw_perf_events(void)
unconstrained = (struct event_constraint)
__EVENT_CONSTRAINT(0, (1ULL << x86_pmu.num_counters) - 1,
- 0, x86_pmu.num_counters);
+ 0, x86_pmu.num_counters, 0);
if (x86_pmu.event_constraints) {
for_each_event_constraint(c, x86_pmu.event_constraints) {
diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index b9698d40ac4b..51a985cbc12f 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -45,6 +45,7 @@ struct event_constraint {
u64 code;
u64 cmask;
int weight;
+ int overlap;
};
struct amd_nb {
@@ -151,15 +152,40 @@ struct cpu_hw_events {
void *kfree_on_online;
};
-#define __EVENT_CONSTRAINT(c, n, m, w) {\
+#define __EVENT_CONSTRAINT(c, n, m, w, o) {\
{ .idxmsk64 = (n) }, \
.code = (c), \
.cmask = (m), \
.weight = (w), \
+ .overlap = (o), \
}
#define EVENT_CONSTRAINT(c, n, m) \
- __EVENT_CONSTRAINT(c, n, m, HWEIGHT(n))
+ __EVENT_CONSTRAINT(c, n, m, HWEIGHT(n), 0)
+
+/*
+ * The overlap flag marks event constraints with overlapping counter
+ * masks. This is the case if the counter mask of such an event is not
+ * a subset of any other counter mask of a constraint with an equal or
+ * higher weight, e.g.:
+ *
+ * c_overlaps = EVENT_CONSTRAINT_OVERLAP(0, 0x09, 0);
+ * c_another1 = EVENT_CONSTRAINT(0, 0x07, 0);
+ * c_another2 = EVENT_CONSTRAINT(0, 0x38, 0);
+ *
+ * The event scheduler may not select the correct counter in the first
+ * cycle because it needs to know which subsequent events will be
+ * scheduled. It may fail to schedule the events then. So we set the
+ * overlap flag for such constraints to give the scheduler a hint which
+ * events to select for counter rescheduling.
+ *
+ * Care must be taken as the rescheduling algorithm is O(n!) which
+ * will increase scheduling cycles for an over-commited system
+ * dramatically. The number of such EVENT_CONSTRAINT_OVERLAP() macros
+ * and its counter masks must be kept at a minimum.
+ */
+#define EVENT_CONSTRAINT_OVERLAP(c, n, m) \
+ __EVENT_CONSTRAINT(c, n, m, HWEIGHT(n), 1)
/*
* Constraint on the Event code.
diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c
index aeefd45697a2..0397b23be8e9 100644
--- a/arch/x86/kernel/cpu/perf_event_amd.c
+++ b/arch/x86/kernel/cpu/perf_event_amd.c
@@ -492,7 +492,7 @@ static __initconst const struct x86_pmu amd_pmu = {
static struct event_constraint amd_f15_PMC0 = EVENT_CONSTRAINT(0, 0x01, 0);
static struct event_constraint amd_f15_PMC20 = EVENT_CONSTRAINT(0, 0x07, 0);
static struct event_constraint amd_f15_PMC3 = EVENT_CONSTRAINT(0, 0x08, 0);
-static struct event_constraint amd_f15_PMC30 = EVENT_CONSTRAINT(0, 0x09, 0);
+static struct event_constraint amd_f15_PMC30 = EVENT_CONSTRAINT_OVERLAP(0, 0x09, 0);
static struct event_constraint amd_f15_PMC50 = EVENT_CONSTRAINT(0, 0x3F, 0);
static struct event_constraint amd_f15_PMC53 = EVENT_CONSTRAINT(0, 0x38, 0);