[RESEND PATCH v4 2/5] MIPS/Perf-events: Work with the new PMU interface

From: Deng-Cheng Zhu
Date: Mon Jan 24 2011 - 02:36:02 EST

This is the MIPS part of the following commits by Peter Zijlstra:

- a4eaf7f14675cb512d69f0c928055e73d0c6d252
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

For MIPSXX, the stopped state is implemented in the way of 1.b as above.

- 33696fc0d141bbbcb12f75b69608ea83282e3117
perf: Per PMU disable

Changes perf_disable() into perf_pmu_disable().

- 24cd7f54a0d47e1d5b3de29e2456bfbd2d8447b7
perf: Reduce perf_disable() usage

Since the current perf_disable() usage is only an optimization,
remove it for now. This eases the removal of the __weak
hw_perf_enable() interface.

- b0a873ebbf87bf38bf70b5e39a7cadc96099fa13
perf: Register PMU implementations

Simple registration interface for struct pmu, this provides the
infrastructure for removing all the weak functions.

- 51b0fe39549a04858001922919ab355dee9bdfcf
perf: Deconstify struct pmu

sed -ie 's/const struct pmu\>/struct pmu/g' `git grep -l "const struct pmu\>"`

Reported-by: Wu Zhangjin <wuzhangjin@xxxxxxxxx>
Acked-by: David Daney <ddaney@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@xxxxxxxxx>
---
Changes:
v4 - v3:
o Rebase this patch set to have early_initcall instead of arch_initcall for
init_hw_perf_events.
o Change the arguments of perf_pmu_register().
v3 - v2:
o Keep all mentioned commits in the form of number + title + original
summary + (MIPS specific info when needed).
v2 - v1:
o None

arch/mips/kernel/perf_event.c | 275 +++++++++++++++++++---------------
arch/mips/kernel/perf_event_mipsxx.c | 2 +
2 files changed, 158 insertions(+), 119 deletions(-)

diff --git a/arch/mips/kernel/perf_event.c b/arch/mips/kernel/perf_event.c
index 2b7f3f7..1ee44a3 100644
--- a/arch/mips/kernel/perf_event.c
+++ b/arch/mips/kernel/perf_event.c
@@ -161,41 +161,6 @@ mipspmu_event_set_period(struct perf_event *event,
return ret;
}

-static int mipspmu_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;
- int err = 0;
-
- /* To look for a free counter for this event. */
- idx = mipspmu->alloc_counter(cpuc, hwc);
- if (idx < 0) {
- err = idx;
- goto out;
- }
-
- /*
- * If there is an event in the counter we are going to use then
- * make sure it is disabled.
- */
- event->hw.idx = idx;
- mipspmu->disable_event(idx);
- cpuc->events[idx] = event;
-
- /* Set the period for the event. */
- mipspmu_event_set_period(event, hwc, idx);
-
- /* Enable the event. */
- mipspmu->enable_event(hwc, idx);
-
- /* Propagate our changes to the userspace mapping. */
- perf_event_update_userpage(event);
-
-out:
- return err;
-}
-
static void mipspmu_event_update(struct perf_event *event,
struct hw_perf_event *hwc,
int idx)
@@ -231,32 +196,90 @@ again:
return;
}

-static void mipspmu_disable(struct perf_event *event)
+static void mipspmu_start(struct perf_event *event, int flags)
+{
+ struct hw_perf_event *hwc = &event->hw;
+
+ if (!mipspmu)
+ return;
+
+ if (flags & PERF_EF_RELOAD)
+ WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
+
+ hwc->state = 0;
+
+ /* Set the period for the event. */
+ mipspmu_event_set_period(event, hwc, hwc->idx);
+
+ /* Enable the event. */
+ mipspmu->enable_event(hwc, hwc->idx);
+}
+
+static void mipspmu_stop(struct perf_event *event, int flags)
+{
+ struct hw_perf_event *hwc = &event->hw;
+
+ if (!mipspmu)
+ return;
+
+ if (!(hwc->state & PERF_HES_STOPPED)) {
+ /* We are working on a local event. */
+ mipspmu->disable_event(hwc->idx);
+ barrier();
+ mipspmu_event_update(event, hwc, hwc->idx);
+ hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
+ }
+}
+
+static int mipspmu_add(struct perf_event *event, int flags)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
struct hw_perf_event *hwc = &event->hw;
- int idx = hwc->idx;
+ int idx;
+ int err = 0;

+ perf_pmu_disable(event->pmu);

- WARN_ON(idx < 0 || idx >= mipspmu->num_counters);
+ /* To look for a free counter for this event. */
+ idx = mipspmu->alloc_counter(cpuc, hwc);
+ if (idx < 0) {
+ err = idx;
+ goto out;
+ }

- /* We are working on a local event. */
+ /*
+ * If there is an event in the counter we are going to use then
+ * make sure it is disabled.
+ */
+ event->hw.idx = idx;
mipspmu->disable_event(idx);
+ cpuc->events[idx] = event;

- barrier();
-
- mipspmu_event_update(event, hwc, idx);
- cpuc->events[idx] = NULL;
- clear_bit(idx, cpuc->used_mask);
+ hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
+ if (flags & PERF_EF_START)
+ mipspmu_start(event, PERF_EF_RELOAD);

+ /* Propagate our changes to the userspace mapping. */
perf_event_update_userpage(event);
+
+out:
+ perf_pmu_enable(event->pmu);
+ return err;
}

-static void mipspmu_unthrottle(struct perf_event *event)
+static void mipspmu_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;
+ int idx = hwc->idx;

- mipspmu->enable_event(hwc, hwc->idx);
+ WARN_ON(idx < 0 || idx >= mipspmu->num_counters);
+
+ mipspmu_stop(event, PERF_EF_UPDATE);
+ cpuc->events[idx] = NULL;
+ clear_bit(idx, cpuc->used_mask);
+
+ perf_event_update_userpage(event);
}

static void mipspmu_read(struct perf_event *event)
@@ -270,12 +293,17 @@ static void mipspmu_read(struct perf_event *event)
mipspmu_event_update(event, hwc, hwc->idx);
}

-static struct pmu pmu = {
- .enable = mipspmu_enable,
- .disable = mipspmu_disable,
- .unthrottle = mipspmu_unthrottle,
- .read = mipspmu_read,
-};
+static void mipspmu_enable(struct pmu *pmu)
+{
+ if (mipspmu)
+ mipspmu->start();
+}
+
+static void mipspmu_disable(struct pmu *pmu)
+{
+ if (mipspmu)
+ mipspmu->stop();
+}

static atomic_t active_events = ATOMIC_INIT(0);
static DEFINE_MUTEX(pmu_reserve_mutex);
@@ -318,6 +346,82 @@ static void mipspmu_free_irq(void)
perf_irq = save_perf_irq;
}

+/*
+ * mipsxx/rm9000/loongson2 have different performance counters, they have
+ * specific low-level init routines.
+ */
+static void reset_counters(void *arg);
+static int __hw_perf_event_init(struct perf_event *event);
+
+static void hw_perf_event_destroy(struct perf_event *event)
+{
+ if (atomic_dec_and_mutex_lock(&active_events,
+ &pmu_reserve_mutex)) {
+ /*
+ * We must not call the destroy function with interrupts
+ * disabled.
+ */
+ on_each_cpu(reset_counters,
+ (void *)(long)mipspmu->num_counters, 1);
+ mipspmu_free_irq();
+ mutex_unlock(&pmu_reserve_mutex);
+ }
+}
+
+static int mipspmu_event_init(struct perf_event *event)
+{
+ int err = 0;
+
+ switch (event->attr.type) {
+ case PERF_TYPE_RAW:
+ case PERF_TYPE_HARDWARE:
+ case PERF_TYPE_HW_CACHE:
+ break;
+
+ default:
+ return -ENOENT;
+ }
+
+ if (!mipspmu || event->cpu >= nr_cpumask_bits ||
+ (event->cpu >= 0 && !cpu_online(event->cpu)))
+ return -ENODEV;
+
+ if (!atomic_inc_not_zero(&active_events)) {
+ if (atomic_read(&active_events) > MIPS_MAX_HWEVENTS) {
+ atomic_dec(&active_events);
+ return -ENOSPC;
+ }
+
+ mutex_lock(&pmu_reserve_mutex);
+ if (atomic_read(&active_events) == 0)
+ err = mipspmu_get_irq();
+
+ if (!err)
+ atomic_inc(&active_events);
+ mutex_unlock(&pmu_reserve_mutex);
+ }
+
+ if (err)
+ return err;
+
+ err = __hw_perf_event_init(event);
+ if (err)
+ hw_perf_event_destroy(event);
+
+ return err;
+}
+
+static struct pmu pmu = {
+ .pmu_enable = mipspmu_enable,
+ .pmu_disable = mipspmu_disable,
+ .event_init = mipspmu_event_init,
+ .add = mipspmu_add,
+ .del = mipspmu_del,
+ .start = mipspmu_start,
+ .stop = mipspmu_stop,
+ .read = mipspmu_read,
+};
+
static inline unsigned int
mipspmu_perf_event_encode(const struct mips_perf_event *pev)
{
@@ -409,73 +513,6 @@ static int validate_group(struct perf_event *event)
return 0;
}

-/*
- * mipsxx/rm9000/loongson2 have different performance counters, they have
- * specific low-level init routines.
- */
-static void reset_counters(void *arg);
-static int __hw_perf_event_init(struct perf_event *event);
-
-static void hw_perf_event_destroy(struct perf_event *event)
-{
- if (atomic_dec_and_mutex_lock(&active_events,
- &pmu_reserve_mutex)) {
- /*
- * We must not call the destroy function with interrupts
- * disabled.
- */
- on_each_cpu(reset_counters,
- (void *)(long)mipspmu->num_counters, 1);
- mipspmu_free_irq();
- mutex_unlock(&pmu_reserve_mutex);
- }
-}
-
-const struct pmu *hw_perf_event_init(struct perf_event *event)
-{
- int err = 0;
-
- if (!mipspmu || event->cpu >= nr_cpumask_bits ||
- (event->cpu >= 0 && !cpu_online(event->cpu)))
- return ERR_PTR(-ENODEV);
-
- if (!atomic_inc_not_zero(&active_events)) {
- if (atomic_read(&active_events) > MIPS_MAX_HWEVENTS) {
- atomic_dec(&active_events);
- return ERR_PTR(-ENOSPC);
- }
-
- mutex_lock(&pmu_reserve_mutex);
- if (atomic_read(&active_events) == 0)
- err = mipspmu_get_irq();
-
- if (!err)
- atomic_inc(&active_events);
- mutex_unlock(&pmu_reserve_mutex);
- }
-
- if (err)
- return ERR_PTR(err);
-
- err = __hw_perf_event_init(event);
- if (err)
- hw_perf_event_destroy(event);
-
- return err ? ERR_PTR(err) : &pmu;
-}
-
-void hw_perf_enable(void)
-{
- if (mipspmu)
- mipspmu->start();
-}
-
-void hw_perf_disable(void)
-{
- if (mipspmu)
- mipspmu->stop();
-}
-
/* This is needed by specific irq handlers in perf_event_*.c */
static void
handle_associated_event(struct cpu_hw_events *cpuc,
diff --git a/arch/mips/kernel/perf_event_mipsxx.c b/arch/mips/kernel/perf_event_mipsxx.c
index fa00edc..c9406d6 100644
--- a/arch/mips/kernel/perf_event_mipsxx.c
+++ b/arch/mips/kernel/perf_event_mipsxx.c
@@ -1045,6 +1045,8 @@ init_hw_perf_events(void)
"CPU, irq %d%s\n", mipspmu->name, counters, irq,
irq < 0 ? " (share with timer interrupt)" : "");

+ perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW);
+
return 0;
}
early_initcall(init_hw_perf_events);
--
1.7.1

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