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perf counters: implement PERF_COUNT_CPU_CLOCK 

Impact: add new perf-counter type

The 'CPU clock' counter counts the amount of CPU clock time that is
elapsing, in nanoseconds. (regardless of how much of it the task is
spending on a CPU executing)

This counter type is a Linux kernel based abstraction, it is available
even if the hardware does not support native hardware performance counters.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2008-12-11 13:21:10 +01:00
parent 621a01eac8
commit 5c92d12411
3 changed files with 92 additions and 48 deletions
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36
arch/x86/kernel/cpu/perf_counter.c
View File

@ -178,35 +178,6 @@ static void x86_perf_counter_enable(struct perf_counter *counter)
__x86_perf_counter_enable(hwc, idx);
}
#ifdef CONFIG_X86_64
static inline void atomic64_counter_set(struct perf_counter *counter, u64 val)
{
atomic64_set(&counter->count, val);
}
static inline u64 atomic64_counter_read(struct perf_counter *counter)
{
return atomic64_read(&counter->count);
}
#else
/*
* Todo: add proper atomic64_t support to 32-bit x86:
*/
static inline void atomic64_counter_set(struct perf_counter *counter, u64 val64)
{
u32 *val32 = (void *)&val64;
atomic_set(counter->count32 + 0, *(val32 + 0));
atomic_set(counter->count32 + 1, *(val32 + 1));
}
static inline u64 atomic64_counter_read(struct perf_counter *counter)
{
return atomic_read(counter->count32 + 0) |
(u64) atomic_read(counter->count32 + 1) << 32;
}
#endif
static void __hw_perf_save_counter(struct perf_counter *counter,
struct hw_perf_counter *hwc, int idx)
{
@ -309,7 +280,7 @@ static void x86_perf_counter_read(struct perf_counter *counter)
} while (offs != hwc->prev_count);
val32 = (s32) val;
val = (s64)hwc->irq_period + (s64)val32;
val = (s64)hwc->irq_period + (s64)val32;
atomic64_counter_set(counter, hwc->prev_count + val);
}
@ -573,13 +544,14 @@ void __init init_hw_perf_counters(void)
perf_counters_initialized = true;
}
static struct hw_perf_counter_ops x86_perf_counter_ops = {
static const struct hw_perf_counter_ops x86_perf_counter_ops = {
.hw_perf_counter_enable = x86_perf_counter_enable,
.hw_perf_counter_disable = x86_perf_counter_disable,
.hw_perf_counter_read = x86_perf_counter_read,
};
struct hw_perf_counter_ops *hw_perf_counter_init(struct perf_counter *counter)
const struct hw_perf_counter_ops *
hw_perf_counter_init(struct perf_counter *counter)
{
int err;

9
include/linux/perf_counter.h
View File

@ -131,7 +131,7 @@ struct perf_counter {
struct list_head list_entry;
struct list_head sibling_list;
struct perf_counter *group_leader;
struct hw_perf_counter_ops *hw_ops;
const struct hw_perf_counter_ops *hw_ops;
int active;
#if BITS_PER_LONG == 64
@ -197,7 +197,7 @@ struct perf_cpu_context {
extern int perf_max_counters;
#ifdef CONFIG_PERF_COUNTERS
extern struct hw_perf_counter_ops *
extern const struct hw_perf_counter_ops *
hw_perf_counter_init(struct perf_counter *counter);
extern void perf_counter_task_sched_in(struct task_struct *task, int cpu);
@ -208,6 +208,9 @@ extern void perf_counter_notify(struct pt_regs *regs);
extern void perf_counter_print_debug(void);
extern void hw_perf_restore_ctrl(u64 ctrl);
extern u64 hw_perf_disable_all(void);
extern void atomic64_counter_set(struct perf_counter *counter, u64 val64);
extern u64 atomic64_counter_read(struct perf_counter *counter);
#else
static inline void
perf_counter_task_sched_in(struct task_struct *task, int cpu) { }
@ -219,7 +222,7 @@ static inline void perf_counter_init_task(struct task_struct *task) { }
static inline void perf_counter_notify(struct pt_regs *regs) { }
static inline void perf_counter_print_debug(void) { }
static inline void hw_perf_restore_ctrl(u64 ctrl) { }
static inline u64 hw_perf_disable_all(void) { return 0; }
static inline u64 hw_perf_disable_all(void) { return 0; }
#endif
#endif /* _LINUX_PERF_COUNTER_H */

95
kernel/perf_counter.c
View File

@ -37,15 +37,15 @@ static DEFINE_MUTEX(perf_resource_mutex);
/*
* Architecture provided APIs - weak aliases:
*/
extern __weak struct hw_perf_counter_ops *
extern __weak const struct hw_perf_counter_ops *
hw_perf_counter_init(struct perf_counter *counter)
{
return ERR_PTR(-EINVAL);
}
void __weak hw_perf_disable_all(void) { }
void __weak hw_perf_enable_all(void) { }
void __weak hw_perf_counter_setup(void) { }
u64 __weak hw_perf_disable_all(void) { return 0; }
void __weak hw_perf_restore_ctrl(u64 ctrl) { }
void __weak hw_perf_counter_setup(void) { }
#if BITS_PER_LONG == 64
@ -58,6 +58,16 @@ static inline u64 perf_counter_read_safe(struct perf_counter *counter)
return (u64) atomic64_read(&counter->count);
}
void atomic64_counter_set(struct perf_counter *counter, u64 val)
{
atomic64_set(&counter->count, val);
}
u64 atomic64_counter_read(struct perf_counter *counter)
{
return atomic64_read(&counter->count);
}
#else
/*
@ -79,6 +89,20 @@ static u64 perf_counter_read_safe(struct perf_counter *counter)
return cntl | ((u64) cnth) << 32;
}
void atomic64_counter_set(struct perf_counter *counter, u64 val64)
{
u32 *val32 = (void *)&val64;
atomic_set(counter->count32 + 0, *(val32 + 0));
atomic_set(counter->count32 + 1, *(val32 + 1));
}
u64 atomic64_counter_read(struct perf_counter *counter)
{
return atomic_read(counter->count32 + 0) |
(u64) atomic_read(counter->count32 + 1) << 32;
}
#endif
static void
@ -131,6 +155,7 @@ static void __perf_counter_remove_from_context(void *info)
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_counter *counter = info;
struct perf_counter_context *ctx = counter->ctx;
u64 perf_flags;
/*
* If this is a task context, we need to check whether it is
@ -155,9 +180,9 @@ static void __perf_counter_remove_from_context(void *info)
* Protect the list operation against NMI by disabling the
* counters on a global level. NOP for non NMI based counters.
*/
hw_perf_disable_all();
perf_flags = hw_perf_disable_all();
list_del_counter(counter, ctx);
hw_perf_enable_all();
hw_perf_restore_ctrl(perf_flags);
if (!ctx->task) {
/*
@ -232,6 +257,7 @@ static void __perf_install_in_context(void *info)
struct perf_counter *counter = info;
struct perf_counter_context *ctx = counter->ctx;
int cpu = smp_processor_id();
u64 perf_flags;
/*
* If this is a task context, we need to check whether it is
@ -247,9 +273,9 @@ static void __perf_install_in_context(void *info)
* Protect the list operation against NMI by disabling the
* counters on a global level. NOP for non NMI based counters.
*/
hw_perf_disable_all();
perf_flags = hw_perf_disable_all();
list_add_counter(counter, ctx);
hw_perf_enable_all();
hw_perf_restore_ctrl(perf_flags);
ctx->nr_counters++;
@ -457,6 +483,7 @@ void perf_counter_task_tick(struct task_struct *curr, int cpu)
{
struct perf_counter_context *ctx = &curr->perf_counter_ctx;
struct perf_counter *counter;
u64 perf_flags;
if (likely(!ctx->nr_counters))
return;
@ -468,13 +495,13 @@ void perf_counter_task_tick(struct task_struct *curr, int cpu)
/*
* Rotate the first entry last (works just fine for group counters too):
*/
hw_perf_disable_all();
perf_flags = hw_perf_disable_all();
list_for_each_entry(counter, &ctx->counter_list, list_entry) {
list_del(&counter->list_entry);
list_add_tail(&counter->list_entry, &ctx->counter_list);
break;
}
hw_perf_enable_all();
hw_perf_restore_ctrl(perf_flags);
spin_unlock(&ctx->lock);
@ -807,6 +834,42 @@ static const struct file_operations perf_fops = {
.poll = perf_poll,
};
static void cpu_clock_perf_counter_enable(struct perf_counter *counter)
{
}
static void cpu_clock_perf_counter_disable(struct perf_counter *counter)
{
}
static void cpu_clock_perf_counter_read(struct perf_counter *counter)
{
int cpu = raw_smp_processor_id();
atomic64_counter_set(counter, cpu_clock(cpu));
}
static const struct hw_perf_counter_ops perf_ops_cpu_clock = {
.hw_perf_counter_enable = cpu_clock_perf_counter_enable,
.hw_perf_counter_disable = cpu_clock_perf_counter_disable,
.hw_perf_counter_read = cpu_clock_perf_counter_read,
};
static const struct hw_perf_counter_ops *
sw_perf_counter_init(struct perf_counter *counter)
{
const struct hw_perf_counter_ops *hw_ops = NULL;
switch (counter->hw_event.type) {
case PERF_COUNT_CPU_CLOCK:
hw_ops = &perf_ops_cpu_clock;
break;
default:
break;
}
return hw_ops;
}
/*
* Allocate and initialize a counter structure
*/
@ -815,7 +878,7 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event,
int cpu,
struct perf_counter *group_leader)
{
struct hw_perf_counter_ops *hw_ops;
const struct hw_perf_counter_ops *hw_ops;
struct perf_counter *counter;
counter = kzalloc(sizeof(*counter), GFP_KERNEL);
@ -842,7 +905,13 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event,
counter->group_leader = group_leader;
counter->hw_ops = NULL;
hw_ops = hw_perf_counter_init(counter);
hw_ops = NULL;
if (!hw_event->raw && hw_event->type < 0)
hw_ops = sw_perf_counter_init(counter);
if (!hw_ops) {
hw_ops = hw_perf_counter_init(counter);
}
if (!hw_ops) {
kfree(counter);
return NULL;
@ -912,7 +981,7 @@ asmlinkage int sys_perf_counter_open(
goto err_put_context;
}
ret = -ENOMEM;
ret = -EINVAL;
counter = perf_counter_alloc(&hw_event, cpu, group_leader);
if (!counter)
goto err_put_context;