On 8/28/2019 5:02 AM, Peter Zijlstra wrote:
On Wed, Aug 28, 2019 at 10:44:16AM +0200, Peter Zijlstra wrote:

Let me clean up this mess for you.

Here, how's that. Now we don't check is_metric_idx() _3_ times on the
enable/disable path and all the topdown crud is properly placed in the
fixed counter functions.

Thank you very much for the cleanup. The new code is more efficient.
I will prepare V4 with this code and to address other comments.

Thanks,
Kan

Please think; don't tinker.

---

--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1033,22 +1033,34 @@ static inline void x86_assign_hw_event(s
                                struct cpu_hw_events *cpuc, int i)
  {
        struct hw_perf_event *hwc = &event->hw;
+       int idx;
- hwc->idx = cpuc->assign[i];
+       idx = hwc->idx = cpuc->assign[i];
        hwc->last_cpu = smp_processor_id();
        hwc->last_tag = ++cpuc->tags[i];
- if (hwc->idx == INTEL_PMC_IDX_FIXED_BTS) {
+       switch (hwc->idx) {
+       case INTEL_PMC_IDX_FIXED_BTS:
                hwc->config_base = 0;
                hwc->event_base      = 0;
-       } else if (hwc->idx >= INTEL_PMC_IDX_FIXED) {
+               break;
+
+       case INTEL_PMC_IDX_FIXED_METRIC_BASE ... 
INTEL_PMC_IDX_FIXED_METRIC_BASE+3:
+               /* All METRIC events are mapped onto the fixed SLOTS event */
+               idx = INTEL_PMC_IDX_FIXED_SLOTS;
+
+       case INTEL_PMC_IDX_FIXED ... INTEL_PMC_IDX_FIXED_BTS-1:
                hwc->config_base = MSR_ARCH_PERFMON_FIXED_CTR_CTRL;
-               hwc->event_base = MSR_ARCH_PERFMON_FIXED_CTR0 + (hwc->idx - 
INTEL_PMC_IDX_FIXED);
-               hwc->event_base_rdpmc = (hwc->idx - INTEL_PMC_IDX_FIXED) | 
1<<30;
-       } else {
+               hwc->event_base = MSR_ARCH_PERFMON_FIXED_CTR0 +
+                                 (idx - INTEL_PMC_IDX_FIXED);
+               hwc->event_base_rdpmc = (idx - INTEL_PMC_IDX_FIXED) | 1<<30;
+               break;
+
+       default:
                hwc->config_base = x86_pmu_config_addr(hwc->idx);
                hwc->event_base  = x86_pmu_event_addr(hwc->idx);
                hwc->event_base_rdpmc = x86_pmu_rdpmc_index(hwc->idx);
+               break;
        }
  }
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2128,27 +2128,61 @@ static inline void intel_pmu_ack_status(
        wrmsrl(MSR_CORE_PERF_GLOBAL_OVF_CTRL, ack);
  }
-static void intel_pmu_disable_fixed(struct hw_perf_event *hwc)
+static inline bool event_is_checkpointed(struct perf_event *event)
+{
+       return unlikely(event->hw.config & HSW_IN_TX_CHECKPOINTED) != 0;
+}
+
+static inline void intel_set_masks(struct perf_event *event, int idx)
+{
+       struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+
+       if (event->attr.exclude_host)
+               __set_bit(idx, (unsigned long *)&cpuc->intel_ctrl_guest_mask);
+       if (event->attr.exclude_guest)
+               __set_bit(idx, (unsigned long *)&cpuc->intel_ctrl_host_mask);
+       if (event_is_checkpointed(event))
+               __set_bit(idx, (unsigned long *)&cpuc->intel_cp_status);
+}
+
+static inline void intel_clear_masks(struct perf_event *event, int idx)
  {
-       int idx = hwc->idx - INTEL_PMC_IDX_FIXED;
+       struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+
+       __clear_bit(idx, (unsigned long *)&cpuc->intel_ctrl_guest_mask);
+       __clear_bit(idx, (unsigned long *)&cpuc->intel_ctrl_host_mask);
+       __clear_bit(idx, (unsigned long *)&cpuc->intel_cp_status);
+}
+
+static void intel_pmu_disable_fixed(struct perf_event *event)
+{
+       struct hw_perf_event *hwc = &event->hw;
        u64 ctrl_val, mask;
+       int idx = hwc->idx;
- mask = 0xfULL << (idx * 4);
+       if (is_topdown_idx(idx)) {
+               struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+               /*
+                * When there are other Top-Down events still active; don't
+                * disable the SLOTS counter.
+                */
+               if (*(u64 *)cpuc->active_mask & 
INTEL_PMC_OTHER_TOPDOWN_BITS(idx))
+                       return;
+
+               idx = INTEL_PMC_IDX_FIXED_SLOTS;
+       }
+ intel_clear_masks(event, idx);
+
+       mask = 0xfULL << ((idx - INTEL_PMC_IDX_FIXED) * 4);
        rdmsrl(hwc->config_base, ctrl_val);
        ctrl_val &= ~mask;
        wrmsrl(hwc->config_base, ctrl_val);
  }
-static inline bool event_is_checkpointed(struct perf_event *event)
-{
-       return (event->hw.config & HSW_IN_TX_CHECKPOINTED) != 0;
-}
-
  static void intel_pmu_disable_event(struct perf_event *event)
  {
        struct hw_perf_event *hwc = &event->hw;
-       struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
if (unlikely(hwc->idx == INTEL_PMC_IDX_FIXED_BTS)) {
                intel_pmu_disable_bts();
@@ -2156,18 +2190,19 @@ static void intel_pmu_disable_event(stru
                return;
        }
- cpuc->intel_ctrl_guest_mask &= ~(1ull << hwc->idx);
-       cpuc->intel_ctrl_host_mask &= ~(1ull << hwc->idx);
-       cpuc->intel_cp_status &= ~(1ull << hwc->idx);
-
-       if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL))
-               intel_pmu_disable_fixed(hwc);
-       else
+       if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL)) {
+               intel_pmu_disable_fixed(event);
+       } else {
+               intel_clear_masks(event, hwc->idx);
                x86_pmu_disable_event(event);
+       }
/*
         * Needs to be called after x86_pmu_disable_event,
         * so we don't trigger the event without PEBS bit set.
+        *
+        * Metric stuff doesn't do PEBS (I hope?); and so the early exit from
+        * intel_pmu_disable_fixed() is OK.
         */
        if (unlikely(event->attr.precise_ip))
                intel_pmu_pebs_disable(event);
@@ -2192,8 +2227,22 @@ static void intel_pmu_read_event(struct
  static void intel_pmu_enable_fixed(struct perf_event *event)
  {
        struct hw_perf_event *hwc = &event->hw;
-       int idx = hwc->idx - INTEL_PMC_IDX_FIXED;
        u64 ctrl_val, mask, bits = 0;
+       int idx = hwc->idx;
+
+       if (is_topdown_idx(idx)) {
+               struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+               /*
+                * When there are other Top-Down events already active; don't
+                * enable the SLOTS counter.
+                */
+               if (*(u64 *)cpuc->active_mask & 
INTEL_PMC_OTHER_TOPDOWN_BITS(idx))
+                       return;
+
+               idx = INTEL_PMC_IDX_FIXED_SLOTS;
+       }
+
+       intel_set_masks(event, hwc->idx);
/*
         * Enable IRQ generation (0x8), if not PEBS,
@@ -2213,6 +2262,7 @@ static void intel_pmu_enable_fixed(struc
        if (x86_pmu.version > 2 && hwc->config & ARCH_PERFMON_EVENTSEL_ANY)
                bits |= 0x4;
+ idx -= INTEL_PMC_IDX_FIXED;
        bits <<= (idx * 4);
        mask = 0xfULL << (idx * 4);
@@ -2230,7 +2280,6 @@ static void intel_pmu_enable_fixed(struc
  static void intel_pmu_enable_event(struct perf_event *event)
  {
        struct hw_perf_event *hwc = &event->hw;
-       struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
if (unlikely(hwc->idx == INTEL_PMC_IDX_FIXED_BTS)) {
                if (!__this_cpu_read(cpu_hw_events.enabled))
@@ -2240,23 +2289,16 @@ static void intel_pmu_enable_event(struc
                return;
        }
- if (event->attr.exclude_host)
-               cpuc->intel_ctrl_guest_mask |= (1ull << hwc->idx);
-       if (event->attr.exclude_guest)
-               cpuc->intel_ctrl_host_mask |= (1ull << hwc->idx);
-
-       if (unlikely(event_is_checkpointed(event)))
-               cpuc->intel_cp_status |= (1ull << hwc->idx);
if (unlikely(event->attr.precise_ip))
                intel_pmu_pebs_enable(event);
if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL)) {
                intel_pmu_enable_fixed(event);
-               return;
+       } else {
+               intel_set_masks(event, hwc->idx);
+               __x86_pmu_enable_event(hwc, ARCH_PERFMON_EVENTSEL_ENABLE);
        }
-
-       __x86_pmu_enable_event(hwc, ARCH_PERFMON_EVENTSEL_ENABLE);
  }
static void intel_pmu_add_event(struct perf_event *event)
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -349,6 +349,20 @@ struct cpu_hw_events {
        EVENT_CONSTRAINT(c, (1ULL << (32+n)), FIXED_EVENT_FLAGS)
/*
+ * Special metric counters do not actually exist, but get remapped
+ * to a combination of FxCtr3 + MSR_PERF_METRICS
+ *
+ * This allocates them to a dummy offset for the scheduler.
+ * This does not allow sharing of multiple users of the same
+ * metric without multiplexing, even though the hardware supports that
+ * in principle.
+ */
+
+#define METRIC_EVENT_CONSTRAINT(c, n)                                  \
+       EVENT_CONSTRAINT(c, (1ULL << (INTEL_PMC_IDX_FIXED_METRIC_BASE+n)), \
+                        FIXED_EVENT_FLAGS)
+
+/*
   * Constraint on the Event code + UMask
   */
  #define INTEL_UEVENT_CONSTRAINT(c, n) \
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -795,6 +795,7 @@
  #define MSR_CORE_PERF_FIXED_CTR0      0x00000309
  #define MSR_CORE_PERF_FIXED_CTR1      0x0000030a
  #define MSR_CORE_PERF_FIXED_CTR2      0x0000030b
+#define MSR_CORE_PERF_FIXED_CTR3       0x0000030c
  #define MSR_CORE_PERF_FIXED_CTR_CTRL  0x0000038d
  #define MSR_CORE_PERF_GLOBAL_STATUS   0x0000038e
  #define MSR_CORE_PERF_GLOBAL_CTRL     0x0000038f
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -175,11 +175,39 @@ struct x86_pmu_capability {
  /*
   * We model BTS tracing as another fixed-mode PMC.
   *
- * We choose a value in the middle of the fixed event range, since lower
+ * We choose value 47 for the fixed index of BTS, since lower
   * values are used by actual fixed events and higher values are used
   * to indicate other overflow conditions in the PERF_GLOBAL_STATUS msr.
   */
-#define INTEL_PMC_IDX_FIXED_BTS                                
(INTEL_PMC_IDX_FIXED + 16)
+#define INTEL_PMC_IDX_FIXED_BTS                                
(INTEL_PMC_IDX_FIXED + 15)
+
+/*
+ * We model PERF_METRICS as more magic fixed-mode PMCs, one for each metric
+ *
+ * Internally they all map to Fixed Ctr 3 (SLOTS), and allocate PERF_METRICS
+ * as an extra_reg. PERF_METRICS has no own configuration, but we fill in
+ * the configuration of FxCtr3 to enforce that all the shared users of SLOTS
+ * have the same configuration.
+ */
+#define INTEL_PMC_IDX_FIXED_METRIC_BASE                (INTEL_PMC_IDX_FIXED + 
16)
+#define INTEL_PMC_IDX_TD_RETIRING              
(INTEL_PMC_IDX_FIXED_METRIC_BASE + 0)
+#define INTEL_PMC_IDX_TD_BAD_SPEC              
(INTEL_PMC_IDX_FIXED_METRIC_BASE + 1)
+#define INTEL_PMC_IDX_TD_FE_BOUND              
(INTEL_PMC_IDX_FIXED_METRIC_BASE + 2)
+#define INTEL_PMC_IDX_TD_BE_BOUND              
(INTEL_PMC_IDX_FIXED_METRIC_BASE + 3)
+#define INTEL_PMC_MSK_TOPDOWN                  ((0xfull << 
INTEL_PMC_IDX_FIXED_METRIC_BASE) | \
+                                                INTEL_PMC_MSK_FIXED_SLOTS)
+
+static inline bool is_metric_idx(int idx)
+{
+       return (unsigned)(idx - INTEL_PMC_IDX_FIXED_METRIC_BASE) < 4;
+}
+
+static inline bool is_topdown_idx(int idx)
+{
+       return is_metric_idx(idx) || idx == INTEL_PMC_IDX_FIXED_SLOTS;
+}
+
+#define INTEL_PMC_OTHER_TOPDOWN_BITS(bit)      (~(0x1ull << bit) & 
INTEL_PMC_MSK_TOPDOWN)
#define GLOBAL_STATUS_COND_CHG BIT_ULL(63)
  #define GLOBAL_STATUS_BUFFER_OVF                      BIT_ULL(62)

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