[tip:perf/core] perf, x86: Add simple group validation

tip-bot for Peter Zijlstra
2009-10-09T14:23:39Z

Commit-ID: fe9081cc9bdabb0be953a39ad977cea14e35bce5
Gitweb: http://git.kernel.org/tip/fe9081cc9bdabb0be953a39ad977cea14e35bce5
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Thu, 8 Oct 2009 11:56:07 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 9 Oct 2009 15:56:14 +0200

perf, x86: Add simple group validation

Refuse to add events when the group wouldn't fit onto the PMU
anymore.

Naive implementation.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@gmail.com>
LKML-Reference: <1254911461.26976.239.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/cpu/perf_event.c | 90 +++++++++++++++++++++++++++++---------
1 files changed, 69 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 9c75854..9961d84 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -114,7 +114,8 @@ struct x86_pmu {
u64 intel_ctrl;
void (*enable_bts)(u64 config);
void (*disable_bts)(void);
- int (*get_event_idx)(struct hw_perf_event *hwc);
+ int (*get_event_idx)(struct cpu_hw_events *cpuc,
+ struct hw_perf_event *hwc);
};

static struct x86_pmu x86_pmu __read_mostly;
@@ -523,7 +524,7 @@ static u64 intel_pmu_raw_event(u64 hw_event)
#define CORE_EVNTSEL_UNIT_MASK 0x0000FF00ULL
#define CORE_EVNTSEL_EDGE_MASK 0x00040000ULL
#define CORE_EVNTSEL_INV_MASK 0x00800000ULL
-#define CORE_EVNTSEL_REG_MASK 0xFF000000ULL
+#define CORE_EVNTSEL_REG_MASK 0xFF000000ULL

#define CORE_EVNTSEL_MASK \
(CORE_EVNTSEL_EVENT_MASK | \
@@ -1390,8 +1391,7 @@ static void amd_pmu_enable_event(struct hw_perf_event *hwc, int idx)
x86_pmu_enable_event(hwc, idx);
}

-static int
-fixed_mode_idx(struct perf_event *event, struct hw_perf_event *hwc)
+static int fixed_mode_idx(struct hw_perf_event *hwc)
{
unsigned int hw_event;

@@ -1424,9 +1424,9 @@ fixed_mode_idx(struct perf_event *event, struct hw_perf_event *hwc)
/*
* generic counter allocator: get next free counter
*/
-static int gen_get_event_idx(struct hw_perf_event *hwc)
+static int
+gen_get_event_idx(struct cpu_hw_events *cpuc, struct hw_perf_event *hwc)
{
- struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
int idx;

idx = find_first_zero_bit(cpuc->used_mask, x86_pmu.num_events);
@@ -1436,16 +1436,16 @@ static int gen_get_event_idx(struct hw_perf_event *hwc)
/*
* intel-specific counter allocator: check event constraints
*/
-static int intel_get_event_idx(struct hw_perf_event *hwc)
+static int
+intel_get_event_idx(struct cpu_hw_events *cpuc, struct hw_perf_event *hwc)
{
- struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
const struct event_constraint *event_constraint;
int i, code;

if (!event_constraint)
goto skip;

- code = hwc->config & 0xff;
+ code = hwc->config & CORE_EVNTSEL_EVENT_MASK;

for_each_event_constraint(event_constraint, event_constraint) {
if (code == event_constraint->code) {
@@ -1457,26 +1457,22 @@ static int intel_get_event_idx(struct hw_perf_event *hwc)
}
}
skip:
- return gen_get_event_idx(hwc);
+ return gen_get_event_idx(cpuc, hwc);
}

-/*
- * Find a PMC slot for the freshly enabled / scheduled in event:
- */
-static int x86_pmu_enable(struct perf_event *event)
+static int
+x86_schedule_event(struct cpu_hw_events *cpuc, struct hw_perf_event *hwc)
{
- struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
- struct hw_perf_event *hwc = &event->hw;
int idx;

- idx = fixed_mode_idx(event, hwc);
+ idx = fixed_mode_idx(hwc);
if (idx == X86_PMC_IDX_FIXED_BTS) {
/* BTS is already occupied. */
if (test_and_set_bit(idx, cpuc->used_mask))
return -EAGAIN;

hwc->config_base = 0;
- hwc->event_base = 0;
+ hwc->event_base = 0;
hwc->idx = idx;
} else if (idx >= 0) {
/*
@@ -1499,17 +1495,33 @@ static int x86_pmu_enable(struct perf_event *event)
/* Try to get the previous generic event again */
if (idx == -1 || test_and_set_bit(idx, cpuc->used_mask)) {
try_generic:
- idx = x86_pmu.get_event_idx(hwc);
+ idx = x86_pmu.get_event_idx(cpuc, hwc);
if (idx == -1)
return -EAGAIN;

set_bit(idx, cpuc->used_mask);
hwc->idx = idx;
}
- hwc->config_base = x86_pmu.eventsel;
- hwc->event_base = x86_pmu.perfctr;
+ hwc->config_base = x86_pmu.eventsel;
+ hwc->event_base = x86_pmu.perfctr;
}

+ return idx;
+}
+
+/*
+ * Find a PMC slot for the freshly enabled / scheduled in event:
+ */
+static int x86_pmu_enable(struct perf_event *event)
+{
+ struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+ struct hw_perf_event *hwc = &event->hw;
+ int idx;
+
+ idx = x86_schedule_event(cpuc, hwc);
+ if (idx < 0)
+ return idx;
+
perf_events_lapic_init();

x86_pmu.disable(hwc, idx);
@@ -2212,11 +2224,47 @@ static const struct pmu pmu = {
.unthrottle = x86_pmu_unthrottle,
};

+static int
+validate_event(struct cpu_hw_events *cpuc, struct perf_event *event)
+{
+ struct hw_perf_event fake_event = event->hw;
+
+ if (event->pmu != &pmu)
+ return 0;
+
+ return x86_schedule_event(cpuc, &fake_event);
+}
+
+static int validate_group(struct perf_event *event)
+{
+ struct perf_event *sibling, *leader = event->group_leader;
+ struct cpu_hw_events fake_pmu;
+
+ memset(&fake_pmu, 0, sizeof(fake_pmu));
+
+ if (!validate_event(&fake_pmu, leader))
+ return -ENOSPC;
+
+ list_for_each_entry(sibling, &leader->sibling_list, group_entry) {
+ if (!validate_event(&fake_pmu, sibling))
+ return -ENOSPC;
+ }
+
+ if (!validate_event(&fake_pmu, event))
+ return -ENOSPC;
+
+ return 0;
+}
+
const struct pmu *hw_perf_event_init(struct perf_event *event)
{
int err;

err = __hw_perf_event_init(event);
+ if (!err) {
+ if (event->group_leader != event)
+ err = validate_group(event);
+ }
if (err) {
if (event->destroy)
event->destroy(event);