dect
/
linux-2.6
Archived
13
0
Fork 0
Code Releases Activity

x86, perfcounters: add support for fixed-function pmcs 

Impact: extend performance counter support on x86 Intel CPUs

Modern Intel CPUs have 3 "fixed-function" performance counters, which
count these hardware events:

    Instr_Retired.Any
    CPU_CLK_Unhalted.Core
    CPU_CLK_Unhalted.Ref

Add support for them to the performance counters subsystem.

Their use is transparent to user-space: the counter scheduler is
extended to automatically recognize the cases where a fixed-function
PMC can be utilized instead of a generic PMC. In such cases the
generic PMC is kept available for more counters.

The above fixed-function events map to these generic counter hw events:

        PERF_COUNT_INSTRUCTIONS
        PERF_COUNT_CPU_CYCLES
        PERF_COUNT_BUS_CYCLES

(The 'bus' cycles are in reality often CPU-ish cycles, just with a fixed
 frequency.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2008-12-22 11:10:42 +01:00
parent f650a67235
commit 2f18d1e8d0
2 changed files with 133 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/x86/include/asm/perf_counter.h
View File

@ -23,6 +23,11 @@
#define ARCH_PERFMON_EVENTSEL_OS (1 << 17)
#define ARCH_PERFMON_EVENTSEL_USR (1 << 16)
/*
* Includes eventsel and unit mask as well:
*/
#define ARCH_PERFMON_EVENT_MASK 0xffff
#define ARCH_PERFMON_UNHALTED_CORE_CYCLES_SEL 0x3c
#define ARCH_PERFMON_UNHALTED_CORE_CYCLES_UMASK (0x00 << 8)
#define ARCH_PERFMON_UNHALTED_CORE_CYCLES_INDEX 0
@ -69,12 +74,15 @@ union cpuid10_edx {
/* Instr_Retired.Any: */
#define MSR_ARCH_PERFMON_FIXED_CTR0 0x309
#define X86_PMC_IDX_FIXED_INSTRUCTIONS (X86_PMC_IDX_FIXED + 0)
/* CPU_CLK_Unhalted.Core: */
#define MSR_ARCH_PERFMON_FIXED_CTR1 0x30a
#define X86_PMC_IDX_FIXED_CPU_CYCLES (X86_PMC_IDX_FIXED + 1)
/* CPU_CLK_Unhalted.Ref: */
#define MSR_ARCH_PERFMON_FIXED_CTR2 0x30b
#define X86_PMC_IDX_FIXED_BUS_CYCLES (X86_PMC_IDX_FIXED + 2)
#ifdef CONFIG_PERF_COUNTERS
extern void init_hw_perf_counters(void);

149
arch/x86/kernel/cpu/perf_counter.c
View File

@ -26,6 +26,7 @@ static bool perf_counters_initialized __read_mostly;
*/
static int nr_counters_generic __read_mostly;
static u64 perf_counter_mask __read_mostly;
static u64 counter_value_mask __read_mostly;
static int nr_counters_fixed __read_mostly;
@ -120,9 +121,6 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
hwc->nmi = 1;
}
hwc->config_base = MSR_ARCH_PERFMON_EVENTSEL0;
hwc->counter_base = MSR_ARCH_PERFMON_PERFCTR0;
hwc->irq_period = hw_event->irq_period;
/*
* Intel PMCs cannot be accessed sanely above 32 bit width,
@ -183,16 +181,34 @@ void hw_perf_restore(u64 ctrl)
}
EXPORT_SYMBOL_GPL(hw_perf_restore);
static inline void
__pmc_fixed_disable(struct perf_counter *counter,
struct hw_perf_counter *hwc, unsigned int __idx)
{
int idx = __idx - X86_PMC_IDX_FIXED;
u64 ctrl_val, mask;
int err;
mask = 0xfULL << (idx * 4);
rdmsrl(hwc->config_base, ctrl_val);
ctrl_val &= ~mask;
err = checking_wrmsrl(hwc->config_base, ctrl_val);
}
static inline void
__pmc_generic_disable(struct perf_counter *counter,
struct hw_perf_counter *hwc, unsigned int idx)
{
int err;
if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL))
return __pmc_fixed_disable(counter, hwc, idx);
err = wrmsr_safe(hwc->config_base + idx, hwc->config, 0);
}
static DEFINE_PER_CPU(u64, prev_left[X86_PMC_MAX_GENERIC]);
static DEFINE_PER_CPU(u64, prev_left[X86_PMC_IDX_MAX]);
/*
* Set the next IRQ period, based on the hwc->period_left value.
@ -202,8 +218,9 @@ static void
__hw_perf_counter_set_period(struct perf_counter *counter,
struct hw_perf_counter *hwc, int idx)
{
s32 left = atomic64_read(&hwc->period_left);
s64 left = atomic64_read(&hwc->period_left);
s32 period = hwc->irq_period;
int err;
/*
* If we are way outside a reasoable range then just skip forward:
@ -224,21 +241,64 @@ __hw_perf_counter_set_period(struct perf_counter *counter,
* The hw counter starts counting from this counter offset,
* mark it to be able to extra future deltas:
*/
atomic64_set(&hwc->prev_count, (u64)(s64)-left);
atomic64_set(&hwc->prev_count, (u64)-left);
wrmsr(hwc->counter_base + idx, -left, 0);
err = checking_wrmsrl(hwc->counter_base + idx,
(u64)(-left) & counter_value_mask);
}
static inline void
__pmc_fixed_enable(struct perf_counter *counter,
struct hw_perf_counter *hwc, unsigned int __idx)
{
int idx = __idx - X86_PMC_IDX_FIXED;
u64 ctrl_val, bits, mask;
int err;
/*
* Enable IRQ generation (0x8) and ring-3 counting (0x2),
* and enable ring-0 counting if allowed:
*/
bits = 0x8ULL | 0x2ULL;
if (hwc->config & ARCH_PERFMON_EVENTSEL_OS)
bits |= 0x1;
bits <<= (idx * 4);
mask = 0xfULL << (idx * 4);
rdmsrl(hwc->config_base, ctrl_val);
ctrl_val &= ~mask;
ctrl_val |= bits;
err = checking_wrmsrl(hwc->config_base, ctrl_val);
}
static void
__pmc_generic_enable(struct perf_counter *counter,
struct hw_perf_counter *hwc, int idx)
{
if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL))
return __pmc_fixed_enable(counter, hwc, idx);
wrmsr(hwc->config_base + idx,
hwc->config | ARCH_PERFMON_EVENTSEL0_ENABLE, 0);
}
static int fixed_mode_idx(struct hw_perf_counter *hwc)
static int
fixed_mode_idx(struct perf_counter *counter, struct hw_perf_counter *hwc)
{
unsigned int event;
if (unlikely(hwc->nmi))
return -1;
event = hwc->config & ARCH_PERFMON_EVENT_MASK;
if (unlikely(event == intel_perfmon_event_map[PERF_COUNT_INSTRUCTIONS]))
return X86_PMC_IDX_FIXED_INSTRUCTIONS;
if (unlikely(event == intel_perfmon_event_map[PERF_COUNT_CPU_CYCLES]))
return X86_PMC_IDX_FIXED_CPU_CYCLES;
if (unlikely(event == intel_perfmon_event_map[PERF_COUNT_BUS_CYCLES]))
return X86_PMC_IDX_FIXED_BUS_CYCLES;
return -1;
}
@ -249,16 +309,39 @@ static int pmc_generic_enable(struct perf_counter *counter)
{
struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
struct hw_perf_counter *hwc = &counter->hw;
int idx = hwc->idx;
int idx;
/* Try to get the previous counter again */
if (test_and_set_bit(idx, cpuc->used)) {
idx = find_first_zero_bit(cpuc->used, nr_counters_generic);
if (idx == nr_counters_generic)
return -EAGAIN;
idx = fixed_mode_idx(counter, hwc);
if (idx >= 0) {
/*
* Try to get the fixed counter, if that is already taken
* then try to get a generic counter:
*/
if (test_and_set_bit(idx, cpuc->used))
goto try_generic;
set_bit(idx, cpuc->used);
hwc->config_base = MSR_ARCH_PERFMON_FIXED_CTR_CTRL;
/*
* We set it so that counter_base + idx in wrmsr/rdmsr maps to
* MSR_ARCH_PERFMON_FIXED_CTR0 ... CTR2:
*/
hwc->counter_base =
MSR_ARCH_PERFMON_FIXED_CTR0 - X86_PMC_IDX_FIXED;
hwc->idx = idx;
} else {
idx = hwc->idx;
/* Try to get the previous generic counter again */
if (test_and_set_bit(idx, cpuc->used)) {
try_generic:
idx = find_first_zero_bit(cpuc->used, nr_counters_generic);
if (idx == nr_counters_generic)
return -EAGAIN;
set_bit(idx, cpuc->used);
hwc->idx = idx;
}
hwc->config_base = MSR_ARCH_PERFMON_EVENTSEL0;
hwc->counter_base = MSR_ARCH_PERFMON_PERFCTR0;
}
perf_counters_lapic_init(hwc->nmi);
@ -266,6 +349,10 @@ static int pmc_generic_enable(struct perf_counter *counter)
__pmc_generic_disable(counter, hwc, idx);
cpuc->counters[idx] = counter;
/*
* Make it visible before enabling the hw:
*/
smp_wmb();
__hw_perf_counter_set_period(counter, hwc, idx);
__pmc_generic_enable(counter, hwc, idx);
@ -275,7 +362,7 @@ static int pmc_generic_enable(struct perf_counter *counter)
void perf_counter_print_debug(void)
{
u64 ctrl, status, overflow, pmc_ctrl, pmc_count, prev_left;
u64 ctrl, status, overflow, pmc_ctrl, pmc_count, prev_left, fixed;
struct cpu_hw_counters *cpuc;
int cpu, idx;
@ -290,11 +377,13 @@ void perf_counter_print_debug(void)
rdmsrl(MSR_CORE_PERF_GLOBAL_CTRL, ctrl);
rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status);
rdmsrl(MSR_CORE_PERF_GLOBAL_OVF_CTRL, overflow);
rdmsrl(MSR_ARCH_PERFMON_FIXED_CTR_CTRL, fixed);
printk(KERN_INFO "\n");
printk(KERN_INFO "CPU#%d: ctrl: %016llx\n", cpu, ctrl);
printk(KERN_INFO "CPU#%d: status: %016llx\n", cpu, status);
printk(KERN_INFO "CPU#%d: overflow: %016llx\n", cpu, overflow);
printk(KERN_INFO "CPU#%d: fixed: %016llx\n", cpu, fixed);
printk(KERN_INFO "CPU#%d: used: %016llx\n", cpu, *(u64 *)cpuc->used);
for (idx = 0; idx < nr_counters_generic; idx++) {
@ -303,13 +392,19 @@ void perf_counter_print_debug(void)
prev_left = per_cpu(prev_left[idx], cpu);
printk(KERN_INFO "CPU#%d: PMC%d ctrl: %016llx\n",
printk(KERN_INFO "CPU#%d: gen-PMC%d ctrl: %016llx\n",
cpu, idx, pmc_ctrl);
printk(KERN_INFO "CPU#%d: PMC%d count: %016llx\n",
printk(KERN_INFO "CPU#%d: gen-PMC%d count: %016llx\n",
cpu, idx, pmc_count);
printk(KERN_INFO "CPU#%d: PMC%d left: %016llx\n",
printk(KERN_INFO "CPU#%d: gen-PMC%d left: %016llx\n",
cpu, idx, prev_left);
}
for (idx = 0; idx < nr_counters_fixed; idx++) {
rdmsrl(MSR_ARCH_PERFMON_FIXED_CTR0 + idx, pmc_count);
printk(KERN_INFO "CPU#%d: fixed-PMC%d count: %016llx\n",
cpu, idx, pmc_count);
}
local_irq_enable();
}
@ -323,6 +418,11 @@ static void pmc_generic_disable(struct perf_counter *counter)
clear_bit(idx, cpuc->used);
cpuc->counters[idx] = NULL;
/*
* Make sure the cleared pointer becomes visible before we
* (potentially) free the counter:
*/
smp_wmb();
/*
* Drain the remaining delta count out of a counter
@ -353,14 +453,11 @@ static void perf_save_and_restart(struct perf_counter *counter)
{
struct hw_perf_counter *hwc = &counter->hw;
int idx = hwc->idx;
u64 pmc_ctrl;
rdmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + idx, pmc_ctrl);
x86_perf_counter_update(counter, hwc, idx);
__hw_perf_counter_set_period(counter, hwc, idx);
if (pmc_ctrl & ARCH_PERFMON_EVENTSEL0_ENABLE)
if (counter->state == PERF_COUNTER_STATE_ACTIVE)
__pmc_generic_enable(counter, hwc, idx);
}
@ -373,6 +470,7 @@ perf_handle_group(struct perf_counter *sibling, u64 *status, u64 *overflown)
* Store sibling timestamps (if any):
*/
list_for_each_entry(counter, &group_leader->sibling_list, list_entry) {
x86_perf_counter_update(counter, &counter->hw, counter->hw.idx);
perf_store_irq_data(sibling, counter->hw_event.type);
perf_store_irq_data(sibling, atomic64_read(&counter->count));
@ -403,7 +501,7 @@ static void __smp_perf_counter_interrupt(struct pt_regs *regs, int nmi)
again:
ack = status;
for_each_bit(bit, (unsigned long *) &status, nr_counters_generic) {
for_each_bit(bit, (unsigned long *)&status, X86_PMC_IDX_MAX) {
struct perf_counter *counter = cpuc->counters[bit];
clear_bit(bit, (unsigned long *) &status);
@ -561,6 +659,9 @@ void __init init_hw_perf_counters(void)
perf_max_counters = nr_counters_generic;
printk(KERN_INFO "... bit width: %d\n", eax.split.bit_width);
counter_value_mask = (1ULL << eax.split.bit_width) - 1;
printk(KERN_INFO "... value mask: %016Lx\n", counter_value_mask);
printk(KERN_INFO "... mask length: %d\n", eax.split.mask_length);
nr_counters_fixed = edx.split.num_counters_fixed;