perf: Rework the PMU methods

Replace pmu::{enable,disable,start,stop,unthrottle} with
pmu::{add,del,start,stop}, all of which take a flags argument.

The new interface extends the capability to stop a counter while
keeping it scheduled on the PMU. We replace the throttled state with
the generic stopped state.

This also allows us to efficiently stop/start counters over certain
code paths (like IRQ handlers).

It also allows scheduling a counter without it starting, allowing for
a generic frozen state (useful for rotating stopped counters).

The stopped state is implemented in two different ways, depending on
how the architecture implemented the throttled state:

 1) We disable the counter:
    a) the pmu has per-counter enable bits, we flip that
    b) we program a NOP event, preserving the counter state

 2) We store the counter state and ignore all read/overflow events

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus <paulus@samba.org>
Cc: stephane eranian <eranian@googlemail.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Yanmin <yanmin_zhang@linux.intel.com>
Cc: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
Cc: David Miller <davem@davemloft.net>
Cc: Michael Cree <mcree@orcon.net.nz>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 53 insertions, 18 deletions

diff --git a/arch/alpha/kernel/perf_event.c b/arch/alpha/kernel/perf_event.c
index 3e260731f8e6..380ef02d557a 100644
--- a/arch/alpha/kernel/perf_event.c
+++ b/arch/alpha/kernel/perf_event.c
@@ -307,7 +307,7 @@ again:
                              new_raw_count) != prev_raw_count)
                 goto again;
 
-        delta = (new_raw_count  - (prev_raw_count & alpha_pmu->pmc_count_mask[idx])) + ovf;
+        delta = (new_raw_count - (prev_raw_count & alpha_pmu->pmc_count_mask[idx])) + ovf;
 
         /* It is possible on very rare occasions that the PMC has overflowed
          * but the interrupt is yet to come.  Detect and fix this situation.
@@ -402,14 +402,13 @@ static void maybe_change_configuration(struct cpu_hw_events *cpuc)
                 struct hw_perf_event *hwc = &pe->hw;
                 int idx = hwc->idx;
 
-                if (cpuc->current_idx[j] != PMC_NO_INDEX) {
-                        cpuc->idx_mask |= (1<<cpuc->current_idx[j]);
-                        continue;
+                if (cpuc->current_idx[j] == PMC_NO_INDEX) {
+                        alpha_perf_event_set_period(pe, hwc, idx);
+                        cpuc->current_idx[j] = idx;
                 }
 
-                alpha_perf_event_set_period(pe, hwc, idx);
-                cpuc->current_idx[j] = idx;
-                cpuc->idx_mask |= (1<<cpuc->current_idx[j]);
+                if (!(hwc->state & PERF_HES_STOPPED))
+                        cpuc->idx_mask |= (1<<cpuc->current_idx[j]);
         }
         cpuc->config = cpuc->event[0]->hw.config_base;
 }
@@ -420,7 +419,7 @@ static void maybe_change_configuration(struct cpu_hw_events *cpuc)
  *  - this function is called from outside this module via the pmu struct
  *    returned from perf event initialisation.
  */
-static int alpha_pmu_enable(struct perf_event *event)
+static int alpha_pmu_add(struct perf_event *event, int flags)
 {
         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
         int n0;
@@ -455,6 +454,10 @@ static int alpha_pmu_enable(struct perf_event *event)
                 }
         }
 
+        hwc->state = PERF_HES_UPTODATE;
+        if (!(flags & PERF_EF_START))
+                hwc->state |= PERF_HES_STOPPED;
+
         local_irq_restore(flags);
         perf_pmu_enable(event->pmu);
 
@@ -467,7 +470,7 @@ static int alpha_pmu_enable(struct perf_event *event)
  *  - this function is called from outside this module via the pmu struct
  *    returned from perf event initialisation.
  */
-static void alpha_pmu_disable(struct perf_event *event)
+static void alpha_pmu_del(struct perf_event *event, int flags)
 {
         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
         struct hw_perf_event *hwc = &event->hw;
@@ -514,13 +517,44 @@ static void alpha_pmu_read(struct perf_event *event)
 }
 
 
-static void alpha_pmu_unthrottle(struct perf_event *event)
+static void alpha_pmu_stop(struct perf_event *event, int flags)
 {
         struct hw_perf_event *hwc = &event->hw;
         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 
+        if (!(hwc->state & PERF_HES_STOPPED)) {
+                cpuc->idx_mask &= !(1UL<<hwc->idx);
+                hwc->state |= PERF_HES_STOPPED;
+        }
+
+        if ((flags & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) {
+                alpha_perf_event_update(event, hwc, hwc->idx, 0);
+                hwc->state |= PERF_HES_UPTODATE;
+        }
+
+        if (cpuc->enabled)
+                wrperfmon(PERFMON_CMD_ENABLE, (1UL<<hwc->idx));
+}
+
+
+static void alpha_pmu_start(struct perf_event *event, int flags)
+{
+        struct hw_perf_event *hwc = &event->hw;
+        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+
+        if (WARN_ON_ONCE(!(hwc->state & PERF_HES_STOPPED)))
+                return;
+
+        if (flags & PERF_EF_RELOAD) {
+                WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
+                alpha_perf_event_set_period(event, hwc, hwc->idx);
+        }
+
+        hwc->state = 0;
+
         cpuc->idx_mask |= 1UL<<hwc->idx;
-        wrperfmon(PERFMON_CMD_ENABLE, (1UL<<hwc->idx));
+        if (cpuc->enabled)
+                wrperfmon(PERFMON_CMD_ENABLE, (1UL<<hwc->idx));
 }
 
 
@@ -671,7 +705,7 @@ static int alpha_pmu_event_init(struct perf_event *event)
 /*
  * Main entry point - enable HW performance counters.
  */
-static void alpha_pmu_pmu_enable(struct pmu *pmu)
+static void alpha_pmu_enable(struct pmu *pmu)
 {
         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 
@@ -697,7 +731,7 @@ static void alpha_pmu_pmu_enable(struct pmu *pmu)
  * Main entry point - disable HW performance counters.
  */
 
-static void alpha_pmu_pmu_disable(struct pmu *pmu)
+static void alpha_pmu_disable(struct pmu *pmu)
 {
         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 
@@ -711,13 +745,14 @@ static void alpha_pmu_pmu_disable(struct pmu *pmu)
 }
 
 static struct pmu pmu = {
-        .pmu_enable     = alpha_pmu_pmu_enable,
-        .pmu_disable    = alpha_pmu_pmu_disable,
+        .pmu_enable     = alpha_pmu_enable,
+        .pmu_disable    = alpha_pmu_disable,
         .event_init     = alpha_pmu_event_init,
-        .enable         = alpha_pmu_enable,
-        .disable        = alpha_pmu_disable,
+        .add            = alpha_pmu_add,
+        .del            = alpha_pmu_del,
+        .start          = alpha_pmu_start,
+        .stop           = alpha_pmu_stop,
         .read           = alpha_pmu_read,
-        .unthrottle     = alpha_pmu_unthrottle,
 };