[tip:perf/core] perf: Reduce perf_disable() usage

From: tip-bot for Peter Zijlstra
Date: Thu Sep 09 2010 - 15:49:31 EST

Commit-ID: 24cd7f54a0d47e1d5b3de29e2456bfbd2d8447b7
Gitweb: http://git.kernel.org/tip/24cd7f54a0d47e1d5b3de29e2456bfbd2d8447b7
Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Fri, 11 Jun 2010 17:32:03 +0200
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 9 Sep 2010 20:46:29 +0200

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.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: paulus <paulus@xxxxxxxxx>
Cc: stephane eranian <eranian@xxxxxxxxxxxxxx>
Cc: Robert Richter <robert.richter@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
Cc: Lin Ming <ming.m.lin@xxxxxxxxx>
Cc: Yanmin <yanmin_zhang@xxxxxxxxxxxxxxx>
Cc: Deng-Cheng Zhu <dengcheng.zhu@xxxxxxxxx>
Cc: David Miller <davem@xxxxxxxxxxxxx>
Cc: Michael Cree <mcree@xxxxxxxxxxxx>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
arch/arm/kernel/perf_event.c | 3 ++
arch/powerpc/kernel/perf_event.c | 3 ++
arch/powerpc/kernel/perf_event_fsl_emb.c | 8 +++++-
arch/sh/kernel/perf_event.c | 11 ++++++--
arch/sparc/kernel/perf_event.c | 3 ++
arch/x86/kernel/cpu/perf_event.c | 22 +++++++++++------
include/linux/perf_event.h | 20 ++++++++--------
kernel/perf_event.c | 37 +-----------------------------
8 files changed, 48 insertions(+), 59 deletions(-)

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index f62f9db..afc92c5 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -277,6 +277,8 @@ armpmu_enable(struct perf_event *event)
int idx;
int err = 0;

+ perf_disable();
+
/* If we don't have a space for the counter then finish early. */
idx = armpmu->get_event_idx(cpuc, hwc);
if (idx < 0) {
@@ -303,6 +305,7 @@ armpmu_enable(struct perf_event *event)
perf_event_update_userpage(event);

out:
+ perf_enable();
return err;
}

diff --git a/arch/powerpc/kernel/perf_event.c b/arch/powerpc/kernel/perf_event.c
index 19131b2..c140882 100644
--- a/arch/powerpc/kernel/perf_event.c
+++ b/arch/powerpc/kernel/perf_event.c
@@ -861,6 +861,7 @@ void power_pmu_start_txn(struct pmu *pmu)
{
struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);

+ perf_disable();
cpuhw->group_flag |= PERF_EVENT_TXN;
cpuhw->n_txn_start = cpuhw->n_events;
}
@@ -875,6 +876,7 @@ void power_pmu_cancel_txn(struct pmu *pmu)
struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);

cpuhw->group_flag &= ~PERF_EVENT_TXN;
+ perf_enable();
}

/*
@@ -901,6 +903,7 @@ int power_pmu_commit_txn(struct pmu *pmu)
cpuhw->event[i]->hw.config = cpuhw->events[i];

cpuhw->group_flag &= ~PERF_EVENT_TXN;
+ perf_enable();
return 0;
}

diff --git a/arch/powerpc/kernel/perf_event_fsl_emb.c b/arch/powerpc/kernel/perf_event_fsl_emb.c
index ea6a804..9bc84a7 100644
--- a/arch/powerpc/kernel/perf_event_fsl_emb.c
+++ b/arch/powerpc/kernel/perf_event_fsl_emb.c
@@ -262,7 +262,7 @@ static int collect_events(struct perf_event *group, int max_count,
return n;
}

-/* perf must be disabled, context locked on entry */
+/* context locked on entry */
static int fsl_emb_pmu_enable(struct perf_event *event)
{
struct cpu_hw_events *cpuhw;
@@ -271,6 +271,7 @@ static int fsl_emb_pmu_enable(struct perf_event *event)
u64 val;
int i;

+ perf_disable();
cpuhw = &get_cpu_var(cpu_hw_events);

if (event->hw.config & FSL_EMB_EVENT_RESTRICTED)
@@ -310,15 +311,17 @@ static int fsl_emb_pmu_enable(struct perf_event *event)
ret = 0;
out:
put_cpu_var(cpu_hw_events);
+ perf_enable();
return ret;
}

-/* perf must be disabled, context locked on entry */
+/* context locked on entry */
static void fsl_emb_pmu_disable(struct perf_event *event)
{
struct cpu_hw_events *cpuhw;
int i = event->hw.idx;

+ perf_disable();
if (i < 0)
goto out;

@@ -346,6 +349,7 @@ static void fsl_emb_pmu_disable(struct perf_event *event)
cpuhw->n_events--;

out:
+ perf_enable();
put_cpu_var(cpu_hw_events);
}

diff --git a/arch/sh/kernel/perf_event.c b/arch/sh/kernel/perf_event.c
index 8cb2065..d042989 100644
--- a/arch/sh/kernel/perf_event.c
+++ b/arch/sh/kernel/perf_event.c
@@ -230,11 +230,14 @@ static int sh_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 = hwc->idx;
+ int ret = -EAGAIN;
+
+ perf_disable();

if (test_and_set_bit(idx, cpuc->used_mask)) {
idx = find_first_zero_bit(cpuc->used_mask, sh_pmu->num_events);
if (idx == sh_pmu->num_events)
- return -EAGAIN;
+ goto out;

set_bit(idx, cpuc->used_mask);
hwc->idx = idx;
@@ -248,8 +251,10 @@ static int sh_pmu_enable(struct perf_event *event)
sh_pmu->enable(hwc, idx);

perf_event_update_userpage(event);
-
- return 0;
+ ret = 0;
+out:
+ perf_enable();
+ return ret;
}

static void sh_pmu_read(struct perf_event *event)
diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
index bed4327..d0131de 100644
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -1113,6 +1113,7 @@ static void sparc_pmu_start_txn(struct pmu *pmu)
{
struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);

+ perf_disable();
cpuhw->group_flag |= PERF_EVENT_TXN;
}

@@ -1126,6 +1127,7 @@ static void sparc_pmu_cancel_txn(struct pmu *pmu)
struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);

cpuhw->group_flag &= ~PERF_EVENT_TXN;
+ perf_enable();
}

/*
@@ -1149,6 +1151,7 @@ static int sparc_pmu_commit_txn(struct pmu *pmu)
return -EAGAIN;

cpuc->group_flag &= ~PERF_EVENT_TXN;
+ perf_enable();
return 0;
}

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 2c89264..846070c 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -969,10 +969,11 @@ static int x86_pmu_enable(struct perf_event *event)

hwc = &event->hw;

+ perf_disable();
n0 = cpuc->n_events;
- n = collect_events(cpuc, event, false);
- if (n < 0)
- return n;
+ ret = n = collect_events(cpuc, event, false);
+ if (ret < 0)
+ goto out;

/*
* If group events scheduling transaction was started,
@@ -980,23 +981,26 @@ static int x86_pmu_enable(struct perf_event *event)
* at commit time(->commit_txn) as a whole
*/
if (cpuc->group_flag & PERF_EVENT_TXN)
- goto out;
+ goto done_collect;

ret = x86_pmu.schedule_events(cpuc, n, assign);
if (ret)
- return ret;
+ goto out;
/*
* copy new assignment, now we know it is possible
* will be used by hw_perf_enable()
*/
memcpy(cpuc->assign, assign, n*sizeof(int));

-out:
+done_collect:
cpuc->n_events = n;
cpuc->n_added += n - n0;
cpuc->n_txn += n - n0;

- return 0;
+ ret = 0;
+out:
+ perf_enable();
+ return ret;
}

static int x86_pmu_start(struct perf_event *event)
@@ -1432,6 +1436,7 @@ static void x86_pmu_start_txn(struct pmu *pmu)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);

+ perf_disable();
cpuc->group_flag |= PERF_EVENT_TXN;
cpuc->n_txn = 0;
}
@@ -1451,6 +1456,7 @@ static void x86_pmu_cancel_txn(struct pmu *pmu)
*/
cpuc->n_added -= cpuc->n_txn;
cpuc->n_events -= cpuc->n_txn;
+ perf_enable();
}

/*
@@ -1480,7 +1486,7 @@ static int x86_pmu_commit_txn(struct pmu *pmu)
memcpy(cpuc->assign, assign, n*sizeof(int));

cpuc->group_flag &= ~PERF_EVENT_TXN;
-
+ perf_enable();
return 0;
}

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index ab72f56..243286a 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -564,26 +564,26 @@ struct pmu {
struct list_head entry;

/*
- * Should return -ENOENT when the @event doesn't match this pmu
+ * Should return -ENOENT when the @event doesn't match this PMU.
*/
int (*event_init) (struct perf_event *event);

- int (*enable) (struct perf_event *event);
+ int (*enable) (struct perf_event *event);
void (*disable) (struct perf_event *event);
- int (*start) (struct perf_event *event);
+ int (*start) (struct perf_event *event);
void (*stop) (struct perf_event *event);
void (*read) (struct perf_event *event);
void (*unthrottle) (struct perf_event *event);

/*
- * Group events scheduling is treated as a transaction, add group
- * events as a whole and perform one schedulability test. If the test
- * fails, roll back the whole group
+ * Group events scheduling is treated as a transaction, add
+ * group events as a whole and perform one schedulability test.
+ * If the test fails, roll back the whole group
*/

/*
- * Start the transaction, after this ->enable() doesn't need
- * to do schedulability tests.
+ * Start the transaction, after this ->enable() doesn't need to
+ * do schedulability tests.
*/
void (*start_txn) (struct pmu *pmu);
/*
@@ -594,8 +594,8 @@ struct pmu {
*/
int (*commit_txn) (struct pmu *pmu);
/*
- * Will cancel the transaction, assumes ->disable() is called for
- * each successfull ->enable() during the transaction.
+ * Will cancel the transaction, assumes ->disable() is called
+ * for each successfull ->enable() during the transaction.
*/
void (*cancel_txn) (struct pmu *pmu);
};
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 149ca18..9a98ce9 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -478,11 +478,6 @@ static void __perf_event_remove_from_context(void *info)
return;

raw_spin_lock(&ctx->lock);
- /*
- * Protect the list operation against NMI by disabling the
- * events on a global level.
- */
- perf_disable();

event_sched_out(event, cpuctx, ctx);

@@ -498,7 +493,6 @@ static void __perf_event_remove_from_context(void *info)
perf_max_events - perf_reserved_percpu);
}

- perf_enable();
raw_spin_unlock(&ctx->lock);
}

@@ -803,12 +797,6 @@ static void __perf_install_in_context(void *info)
ctx->is_active = 1;
update_context_time(ctx);

- /*
- * Protect the list operation against NMI by disabling the
- * events on a global level. NOP for non NMI based events.
- */
- perf_disable();
-
add_event_to_ctx(event, ctx);

if (event->cpu != -1 && event->cpu != smp_processor_id())
@@ -850,8 +838,6 @@ static void __perf_install_in_context(void *info)
cpuctx->max_pertask--;

unlock:
- perf_enable();
-
raw_spin_unlock(&ctx->lock);
}

@@ -972,12 +958,10 @@ static void __perf_event_enable(void *info)
if (!group_can_go_on(event, cpuctx, 1)) {
err = -EEXIST;
} else {
- perf_disable();
if (event == leader)
err = group_sched_in(event, cpuctx, ctx);
else
err = event_sched_in(event, cpuctx, ctx);
- perf_enable();
}

if (err) {
@@ -1090,9 +1074,8 @@ static void ctx_sched_out(struct perf_event_context *ctx,
goto out;
update_context_time(ctx);

- perf_disable();
if (!ctx->nr_active)
- goto out_enable;
+ goto out;

if (event_type & EVENT_PINNED) {
list_for_each_entry(event, &ctx->pinned_groups, group_entry)
@@ -1103,9 +1086,6 @@ static void ctx_sched_out(struct perf_event_context *ctx,
list_for_each_entry(event, &ctx->flexible_groups, group_entry)
group_sched_out(event, cpuctx, ctx);
}
-
- out_enable:
- perf_enable();
out:
raw_spin_unlock(&ctx->lock);
}
@@ -1364,8 +1344,6 @@ ctx_sched_in(struct perf_event_context *ctx,

ctx->timestamp = perf_clock();

- perf_disable();
-
/*
* First go through the list and put on any pinned groups
* in order to give them the best chance of going on.
@@ -1377,7 +1355,6 @@ ctx_sched_in(struct perf_event_context *ctx,
if (event_type & EVENT_FLEXIBLE)
ctx_flexible_sched_in(ctx, cpuctx);

- perf_enable();
out:
raw_spin_unlock(&ctx->lock);
}
@@ -1425,8 +1402,6 @@ void perf_event_task_sched_in(struct task_struct *task)
if (cpuctx->task_ctx == ctx)
return;

- perf_disable();
-
/*
* We want to keep the following priority order:
* cpu pinned (that don't need to move), task pinned,
@@ -1439,8 +1414,6 @@ void perf_event_task_sched_in(struct task_struct *task)
ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE);

cpuctx->task_ctx = ctx;
-
- perf_enable();
}

#define MAX_INTERRUPTS (~0ULL)
@@ -1555,11 +1528,9 @@ static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count)
hwc->sample_period = sample_period;

if (local64_read(&hwc->period_left) > 8*sample_period) {
- perf_disable();
perf_event_stop(event);
local64_set(&hwc->period_left, 0);
perf_event_start(event);
- perf_enable();
}
}

@@ -1588,15 +1559,12 @@ static void perf_ctx_adjust_freq(struct perf_event_context *ctx)
*/
if (interrupts == MAX_INTERRUPTS) {
perf_log_throttle(event, 1);
- perf_disable();
event->pmu->unthrottle(event);
- perf_enable();
}

if (!event->attr.freq || !event->attr.sample_freq)
continue;

- perf_disable();
event->pmu->read(event);
now = local64_read(&event->count);
delta = now - hwc->freq_count_stamp;
@@ -1604,7 +1572,6 @@ static void perf_ctx_adjust_freq(struct perf_event_context *ctx)

if (delta > 0)
perf_adjust_period(event, TICK_NSEC, delta);
- perf_enable();
}
raw_spin_unlock(&ctx->lock);
}
@@ -1647,7 +1614,6 @@ void perf_event_task_tick(struct task_struct *curr)
if (!rotate)
return;

- perf_disable();
cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
if (ctx)
task_ctx_sched_out(ctx, EVENT_FLEXIBLE);
@@ -1659,7 +1625,6 @@ void perf_event_task_tick(struct task_struct *curr)
cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
if (ctx)
task_ctx_sched_in(curr, EVENT_FLEXIBLE);
- perf_enable();
}

static int event_enable_on_exec(struct perf_event *event,
--
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