[tip: perf/core] perf/x86/intel: Fix broken fixed event constraints extension
From: tip-bot2 for Kan Liang
Date: Tue Sep 12 2023 - 03:31:47 EST
The following commit has been merged into the perf/core branch of tip:
Commit-ID: 950ecdc672aec9cd29036b2e2535b07c103af494
Gitweb: https://git.kernel.org/tip/950ecdc672aec9cd29036b2e2535b07c103af494
Author: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
AuthorDate: Mon, 11 Sep 2023 06:51:28 -07:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Tue, 12 Sep 2023 08:22:24 +02:00
perf/x86/intel: Fix broken fixed event constraints extension
Unnecessary multiplexing is triggered when running an "instructions"
event on an MTL.
perf stat -e cpu_core/instructions/,cpu_core/instructions/ -a sleep 1
Performance counter stats for 'system wide':
115,489,000 cpu_core/instructions/ (50.02%)
127,433,777 cpu_core/instructions/ (49.98%)
1.002294504 seconds time elapsed
Linux architectural perf events, e.g., cycles and instructions, usually
have dedicated fixed counters. These events also have equivalent events
which can be used in the general-purpose counters. The counters are
precious. In the intel_pmu_check_event_constraints(), perf check/extend
the event constraints of these events. So these events can utilize both
fixed counters and general-purpose counters.
The following cleanup commit:
97588df87b56 ("perf/x86/intel: Add common intel_pmu_init_hybrid()")
forgot adding the intel_pmu_check_event_constraints() into update_pmu_cap().
The architectural perf events cannot utilize the general-purpose counters.
The code to check and update the counters, event constraints and
extra_regs is the same among hybrid systems. Move
intel_pmu_check_hybrid_pmus() to init_hybrid_pmu(), and
emove the duplicate check in update_pmu_cap().
Fixes: 97588df87b56 ("perf/x86/intel: Add common intel_pmu_init_hybrid()")
Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230911135128.2322833-1-kan.liang@xxxxxxxxxxxxxxx
---
arch/x86/events/intel/core.c | 65 ++++++++++++++---------------------
1 file changed, 26 insertions(+), 39 deletions(-)
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 83dfbba..e1543d6 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4598,6 +4598,13 @@ static void intel_pmu_check_num_counters(int *num_counters,
int *num_counters_fixed,
u64 *intel_ctrl, u64 fixed_mask);
+static void intel_pmu_check_event_constraints(struct event_constraint *event_constraints,
+ int num_counters,
+ int num_counters_fixed,
+ u64 intel_ctrl);
+
+static void intel_pmu_check_extra_regs(struct extra_reg *extra_regs);
+
static inline bool intel_pmu_broken_perf_cap(void)
{
/* The Perf Metric (Bit 15) is always cleared */
@@ -4618,12 +4625,6 @@ static void update_pmu_cap(struct x86_hybrid_pmu *pmu)
&eax, &ebx, &ecx, &edx);
pmu->num_counters = fls(eax);
pmu->num_counters_fixed = fls(ebx);
- intel_pmu_check_num_counters(&pmu->num_counters, &pmu->num_counters_fixed,
- &pmu->intel_ctrl, ebx);
- pmu->max_pebs_events = min_t(unsigned, MAX_PEBS_EVENTS, pmu->num_counters);
- pmu->unconstrained = (struct event_constraint)
- __EVENT_CONSTRAINT(0, (1ULL << pmu->num_counters) - 1,
- 0, pmu->num_counters, 0, 0);
}
@@ -4631,6 +4632,16 @@ static void update_pmu_cap(struct x86_hybrid_pmu *pmu)
/* Perf Metric (Bit 15) and PEBS via PT (Bit 16) are hybrid enumeration */
rdmsrl(MSR_IA32_PERF_CAPABILITIES, pmu->intel_cap.capabilities);
}
+}
+
+static void intel_pmu_check_hybrid_pmus(struct x86_hybrid_pmu *pmu)
+{
+ intel_pmu_check_num_counters(&pmu->num_counters, &pmu->num_counters_fixed,
+ &pmu->intel_ctrl, (1ULL << pmu->num_counters_fixed) - 1);
+ pmu->max_pebs_events = min_t(unsigned, MAX_PEBS_EVENTS, pmu->num_counters);
+ pmu->unconstrained = (struct event_constraint)
+ __EVENT_CONSTRAINT(0, (1ULL << pmu->num_counters) - 1,
+ 0, pmu->num_counters, 0, 0);
if (pmu->intel_cap.perf_metrics)
pmu->intel_ctrl |= 1ULL << GLOBAL_CTRL_EN_PERF_METRICS;
@@ -4641,6 +4652,13 @@ static void update_pmu_cap(struct x86_hybrid_pmu *pmu)
pmu->pmu.capabilities |= PERF_PMU_CAP_AUX_OUTPUT;
else
pmu->pmu.capabilities |= ~PERF_PMU_CAP_AUX_OUTPUT;
+
+ intel_pmu_check_event_constraints(pmu->event_constraints,
+ pmu->num_counters,
+ pmu->num_counters_fixed,
+ pmu->intel_ctrl);
+
+ intel_pmu_check_extra_regs(pmu->extra_regs);
}
static struct x86_hybrid_pmu *find_hybrid_pmu_for_cpu(void)
@@ -4696,6 +4714,8 @@ static bool init_hybrid_pmu(int cpu)
if (this_cpu_has(X86_FEATURE_ARCH_PERFMON_EXT))
update_pmu_cap(pmu);
+ intel_pmu_check_hybrid_pmus(pmu);
+
if (!check_hw_exists(&pmu->pmu, pmu->num_counters, pmu->num_counters_fixed))
return false;
@@ -5915,36 +5935,6 @@ static void intel_pmu_check_extra_regs(struct extra_reg *extra_regs)
}
}
-static void intel_pmu_check_hybrid_pmus(u64 fixed_mask)
-{
- struct x86_hybrid_pmu *pmu;
- int i;
-
- for (i = 0; i < x86_pmu.num_hybrid_pmus; i++) {
- pmu = &x86_pmu.hybrid_pmu[i];
-
- intel_pmu_check_num_counters(&pmu->num_counters,
- &pmu->num_counters_fixed,
- &pmu->intel_ctrl,
- fixed_mask);
-
- if (pmu->intel_cap.perf_metrics) {
- pmu->intel_ctrl |= 1ULL << GLOBAL_CTRL_EN_PERF_METRICS;
- pmu->intel_ctrl |= INTEL_PMC_MSK_FIXED_SLOTS;
- }
-
- if (pmu->intel_cap.pebs_output_pt_available)
- pmu->pmu.capabilities |= PERF_PMU_CAP_AUX_OUTPUT;
-
- intel_pmu_check_event_constraints(pmu->event_constraints,
- pmu->num_counters,
- pmu->num_counters_fixed,
- pmu->intel_ctrl);
-
- intel_pmu_check_extra_regs(pmu->extra_regs);
- }
-}
-
static const struct { enum hybrid_pmu_type id; char *name; } intel_hybrid_pmu_type_map[] __initconst = {
{ hybrid_small, "cpu_atom" },
{ hybrid_big, "cpu_core" },
@@ -6869,9 +6859,6 @@ __init int intel_pmu_init(void)
if (!is_hybrid() && x86_pmu.intel_cap.perf_metrics)
x86_pmu.intel_ctrl |= 1ULL << GLOBAL_CTRL_EN_PERF_METRICS;
- if (is_hybrid() && !boot_cpu_has(X86_FEATURE_ARCH_PERFMON_EXT))
- intel_pmu_check_hybrid_pmus((u64)fixed_mask);
-
if (x86_pmu.intel_cap.pebs_timing_info)
x86_pmu.flags |= PMU_FL_RETIRE_LATENCY;